WO2021246697A1 - METHOD FOR FABRICATING β-GA2O3 THIN FILM - Google Patents

METHOD FOR FABRICATING β-GA2O3 THIN FILM Download PDF

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WO2021246697A1
WO2021246697A1 PCT/KR2021/006391 KR2021006391W WO2021246697A1 WO 2021246697 A1 WO2021246697 A1 WO 2021246697A1 KR 2021006391 W KR2021006391 W KR 2021006391W WO 2021246697 A1 WO2021246697 A1 WO 2021246697A1
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gallium oxide
thin film
beta
gallium
oxide thin
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PCT/KR2021/006391
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French (fr)
Korean (ko)
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김지현
박현익
최용하
양수정
배진호
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고려대학교 산학협력단
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/16—Oxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof

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  • the present invention relates to a method for manufacturing a beta gallium oxide thin film, and more particularly, to a method for manufacturing a beta gallium oxide thin film using liquid gallium.
  • Ga 2 O 3 may exist in various phases, and since the ⁇ phase is physically and chemically stable, it is most suitable for device applications.
  • ⁇ -Ga 2 O 3 has high mechanical and chemical stability and an energy bandgap of 4.9 eV, so it is useful as a high withstand voltage, low loss power semiconductor material. It is attracting attention in the power semiconductor market as an oxide semiconductor with In addition, due to such characteristics, ⁇ -Ga 2 O 3 can be applied to semiconductor lasers, field-effect transistors, switching memories, and high-temperature gas sensors. can be
  • ⁇ -Ga 2 O 3 As a method of manufacturing a thin film, there are RF-sputtering deposition method, MBE growth method, MOCVD growth method, sol-gel process, and the like.
  • RF-sputtering deposition method MBE growth method
  • MOCVD growth method MOCVD growth method
  • sol-gel process sol-gel process
  • conventional ⁇ -Ga 2 O 3 According to the thin film manufacturing methods, there are problems in that the substrate on which the thin film can be grown is limited, a high vacuum process and a post process are essential, and the growth unit cost is high.
  • the present invention is to solve the problems of the prior art described above, and an aspect of the present invention is to transfer and press liquid gallium in the form of droplets on a substrate to generate a 2D gallium oxide layer, and to the gallium oxide layer.
  • An object of the present invention is to provide a method for manufacturing a beta gallium oxide thin film for manufacturing a beta gallium oxide thin film by forming a 2D beta gallium oxide layer through heat treatment.
  • Another aspect of the present invention is to provide a method for manufacturing a beta gallium oxide thin film for manufacturing a beta gallium oxide thin film having a multilayer structure by repeatedly performing the transfer, compression and heat treatment processes on the formed beta gallium oxide layer.
  • a beta gallium oxide thin film manufacturing method comprises the steps of (a) transferring liquid gallium on a substrate in the form of droplets; (b) compressing the liquid gallium transferred to a compression plate to form a two-dimensional thin film-type gallium oxide layer; and (c) heat-treating the gallium oxide layer to form a beta gallium oxide layer in the form of a two-dimensional thin film.
  • the step (a) includes: using a micro pipet, dropping the liquid gallium in the form of droplets on the substrate; may include
  • the step (a) comprises: disposing the substrate on a hot plate heated to 30° C. or higher; and dropping the liquid gallium on the substrate.
  • the liquid gallium in the step (b), may be compressed with a compression force of 0.5 to 50 N.
  • the compressed plate in the step (b), may be removed while being spaced apart in a direction perpendicular to the upper surface of the gallium oxide layer.
  • the beta gallium oxide thin film manufacturing method in the step (c), it may be heat-treated at a temperature of 500 ⁇ 1000 °C.
  • the amount of the liquid gallium transferred in step (a), and the compressive force for compressing the liquid gallium in step (b), the The thickness and area of the beta gallium oxide thin film can be controlled.
  • the transfer step, the gallium oxide layer forming step according to the step (b), and the beta gallium oxide layer forming step according to the step (c) are sequentially performed n (n ⁇ 1, natural number) times additionally, so that on the substrate n+1 (n ⁇ 1, natural number) of the beta gallium oxide layers may be stacked on
  • a 2D beta gallium oxide thin film is manufactured by heat-treating a 2D gallium oxide layer produced by transferring and compressing liquid gallium in the form of droplets on a substrate, thereby reducing the thickness of the thin film according to the amount of liquid gallium and compression strength. It can be adjusted to a micro size, and the area of the thin film can also be adjusted.
  • beta gallium oxide Since the vacuum process of the thin film manufacturing method (especially the epitaxial growth method) is not required, a continuous process is possible and a beta gallium oxide thin film can be manufactured in large quantities.
  • the degree of freedom of the growth substrate is high because the effect of
  • 1 to 2 are flowcharts of a method for manufacturing a beta gallium oxide thin film according to an embodiment of the present invention.
  • FIG. 3 is a flowchart of a method for manufacturing a beta gallium oxide thin film according to another embodiment of the present invention.
  • FIG. 4A is a flowchart of a method for manufacturing a beta gallium oxide thin film according to an experimental example
  • FIG. 4B is a microscope image of the gallium oxide thin film before heat treatment
  • FIG. 4C is a height profile of the gallium oxide thin film measured with an atomic force microscope (AFM) profile
  • FIG. 4d is an atomic ratio analysis result of the gallium oxide thin film using x-ray photoelectron spectroscopy (XPS).
  • AFM atomic force microscope
  • FIG. 5a is a Raman spectrum of a gallium oxide thin film that was heat-treated at various temperatures before heat treatment (as-fabricated) according to an experimental example
  • FIG. 5b is an x-ray diffraction pattern (XRD) spectrum
  • FIG. 5c is liberation and translation of tetrahedral-octahedra chain and in-plane Ga 2 O 6 peak intensity (peak intensity) of the heat treatment temperature of a g 3 and a g 5 phonon mode (phonon mode) that is associated with the octahedra related optical mode
  • FIG. 5d is the average crystallite size according to the heat treatment temperature.
  • Figure 6 shows the characteristics of the 2D beta gallium oxide thin film formed by heat treatment at 900 °C according to the experimental example
  • Figure 6a shows the components of the beta gallium oxide thin film calculated from XPS (x-ray photoelectron spectroscopy) data
  • 6b is a photoluminescence (PL) spectrum of the beta gallium oxide thin film
  • FIG. 6c is an absorbance spectrum of the beta gallium oxide thin film measured using UV-vis absorption spectroscopy
  • FIG. 6d is The valence band maximum (VBM) of the beta gallium oxide thin film is shown
  • FIG. 6e shows the VBM-core delta region and the energy band structure of the beta gallium oxide.
  • FIG. 7A is an optical microscope image of a beta gallium oxide thin film grown on a graphene, quartz, Si(100), or sapphire substrate
  • FIG. 7B is an optical microscope image of a beta gallium oxide thin film. It shows the surface roughness (surface topography)
  • Figure 7c is a Raman spectrum (raman spectra) of the beta gallium oxide thin film
  • Figure 7d shows the XRD (x-ray diffraction pattern) spectrum of the beta gallium oxide thin film
  • Figure 7e is an alpha ( The strains of gallium oxide in ⁇ ) and beta ( ⁇ ) phases are shown.
  • 1 to 2 are flowcharts of a method for manufacturing a beta gallium oxide thin film according to an embodiment of the present invention.
  • the beta gallium oxide thin film manufacturing method includes transferring liquid gallium in the form of droplets on a substrate, and transferring liquid gallium to a press plate.
  • transferring liquid gallium in the form of droplets on a substrate By pressing the to form a gallium oxide layer in the form of a two-dimensional thin film, and heat-treating the gallium oxide layer, comprising the steps of forming a beta gallium oxide layer in the form of a two-dimensional thin film.
  • the present invention relates to a method for manufacturing a beta gallium oxide ( ⁇ -Ga 2 O 3 ) thin film.
  • a semiconductor material having a high breakdown voltage and high electron mobility is required.
  • ⁇ -Ga 2 O 3 has high mechanical and chemical stability and an energy band of 4.9 eV. Because it has a gap, it is useful as a high withstand voltage, low-loss power semiconductor material. It is an oxide semiconductor with a breaking strength of 8 MV/cm, which is three times greater than that of SiC and GaN.
  • the beta gallium oxide manufacturing method includes a liquid gallium transfer step (S100), a gallium oxide layer forming step (S200), and a beta gallium oxide layer forming step (S300).
  • the liquid gallium transfer step (S100) is a process of dropping liquid gallium (liquid Ga) onto an arbitrary substrate.
  • the substrate may be made of SiO 2 , Si, sapphire, quartz, Pt, graphene, GaAs, Cu, or the like, but is not particularly limited.
  • the substrate can be washed with acetone/IPA before use. Since the melting point of gallium (Ga) is as low as 29°C, it can be made into a liquid phase by applying heat above the melting point.
  • liquid gallium is transferred onto the substrate. For example, after placing a substrate on a hot-plate heated to a melting point of gallium or higher, that is, 30° C. or higher, liquid gallium may be dropped onto the substrate.
  • the transferred liquid gallium does not spread on the substrate, but maintains a droplet shape.
  • the liquid gallium may be dropped on the substrate in the form of droplets using a micro pipet. Since the amount of liquid gallium affects the thickness and area of the beta gallium oxide thin film, the thickness and area of the thin film can be adjusted according to the amount.
  • the liquid gallium in the form of transferred droplets is compressed. At this time, it can be compressed in a direction perpendicular to the liquid gallium in droplet form using a compression plate.
  • a compression plate it is appropriate to select a substrate having a high flatness for the compression plate. It is preferable that at least one surface in close contact with liquid gallium has a high flatness.
  • the compression force which is the force applied to the pressing plate to compress the liquid gallium, may be 0.5 to 50 N.
  • the range of the compression force is not necessarily limited as described above, and since the thickness and area of the beta gallium oxide thin film are determined according to the compression force applied to the liquid gallium, the range of the compression force may be determined in consideration of this. Thereby, the thickness of the beta gallium oxide thin film can be controlled from several nm to several ⁇ m.
  • the gallium oxide layer in the form of a thin film is formed.
  • the liquid gallium is oxidized during compression, and ultimately a two-dimensional thin film-type gallium oxide layer is formed.
  • the beta gallium oxide layer forming step (S300) is a process of performing heat treatment on the gallium oxide layer.
  • the heat treatment is a process for making the gallium oxide layer into a ⁇ phase, and the phase and crystallinity of the gallium oxide layer can be controlled according to the temperature and time of the heat treatment.
  • Such heat treatment may be performed at normal pressure and in air.
  • the heat treatment temperature is preferably 500 ⁇ 1000 °C.
  • a beta gallium oxide layer can be produced.
  • a beta gallium oxide thin film having a single layer structure is formed.
  • the amount of liquid gallium and compressive strength are obtained by manufacturing a 2D beta gallium oxide thin film by heat-treating a 2D gallium oxide layer produced by transferring and compressing liquid gallium in the form of droplets on a substrate.
  • the thickness of the thin film can be adjusted to a nano to micro size according to the thickness of the thin film, and the area of the thin film can also be adjusted.
  • conventional beta gallium oxide Since the vacuum process of the thin film manufacturing method (especially the epitaxial growth method) is not required, a continuous process is possible and a beta gallium oxide thin film can be manufactured in large quantities.
  • the degree of freedom of the growth substrate is high because the effect of As a result, when a crystalline beta gallium oxide thin film is directly grown on an arbitrary substrate through the present invention, process time and cost are reduced, and the optimized beta gallium oxide-based optical and electronic device can be manufactured through thin film thickness and area control can do it
  • FIG. 3 is a flowchart of a method for manufacturing a beta gallium oxide thin film according to another embodiment of the present invention.
  • the beta gallium oxide thin film manufacturing method is to form a beta gallium oxide thin film having a multi-layer structure, and a single-layer beta gallium oxide layer (hereinafter, the first After forming a beta gallium oxide layer), liquid gallium is transferred in the form of droplets on the first beta gallium oxide layer and compressed to form a second gallium oxide layer, and heat treatment is performed again to perform second beta gallium oxide layer can be formed.
  • a beta gallium oxide layer is formed on the substrate to prepare a substrate/(beta gallium oxide layer) 1 , and a liquid gallium transfer step (S100), a gallium oxide layer forming step (S200), and By sequentially performing the beta gallium oxide layer forming step (S300) n times (n is a natural number greater than or equal to 1), sequentially stacking n+1 (n is a natural number greater than or equal to 1) number of the beta gallium oxide layers on a substrate, A beta gallium oxide thin film substrate/(beta gallium oxide layer) n+1 of the structure can be prepared.
  • the bandgap of a material tends to increase with decreasing thickness, due to the effect of quantum confinement. Accordingly, by controlling the thickness of the beta gallium oxide thin film having a multilayer structure as described above, the band gap can be increased to be higher than that of the bulk beta gallium oxide.
  • the substrate was placed on a hot plate at 75° C., and several mg of liquid gallium metal (99.9999% purity, GalliumLab) was dropped onto the substrate using a micropipette. Then, a two-dimensional gallium oxide thin film sample was pressed by pressing the liquid gallium with a force of 20 to 50 N perpendicular to the substrate with a press plate with a flat surface, and removing it in the vertical direction so as not to cause slip on the press plate. has formed
  • the sample was heat-treated at 500 ⁇ 1000 °C for two hours using a tube furnace (Lindberg/Blue M) under atmospheric conditions. After heat treatment, the sample was immersed in ethanol at 65° C. and gently rubbed to remove residual gallium.
  • the elemental composition of the gallium oxide thin film was analyzed using X-ray photoelectron spectroscopy (PHI 5000 VersaProbe, ULVAC PHI) with monochromatized Al K ⁇ x-ray source.
  • the optical properties of the beta gallium oxide thin film were analyzed under an optical microscope (BX51M, Olympus), UV-vis absorption spectroscope (Lambda 35, PerkinElmer), micro-Raman spectroscopy with 532 nm diode-pumped solid-state laser (Omicron) in It was measured using a back-scattering geometry, and photoluminescence (PL) spectroscopy with 325 nm He-Cd laser (Kimmon Koha Co.) as an excitation source.
  • X-ray photoelectron spectroscopy PHI 5000 VersaProbe, ULVAC PHI
  • the optical properties of the beta gallium oxide thin film were analyzed under an optical microscope (BX51M, Olympus), UV-vis
  • the thickness and surface morphology of the beta gallium oxide thin film were analyzed in tapping mode using an atomic force microscope (AFM).
  • the crystallinity of the beta gallium oxide thin film was analyzed by X-ray diffraction (XRD, D8 Discover, Bruker) with Cu-K ⁇ radiation.
  • FIG. 4A is a flowchart of a method for manufacturing a beta gallium oxide thin film according to an experimental example
  • FIG. 4B is a microscope image of the gallium oxide thin film before heat treatment
  • FIG. 4C is a height profile of the gallium oxide thin film measured with an atomic force microscope (AFM) profile
  • FIG. 4d is an atomic ratio analysis result of the gallium oxide thin film using x-ray photoelectron spectroscopy (XPS).
  • AFM atomic force microscope
  • the beta gallium oxide thin film according to the experimental example is obtained through two steps, such as squeezing and thermal annealing of liquid gallium.
  • Metals with low melting points Ga, In, Sn, etc.
  • Cabrera-Mott kinetics in air a temperature above the melting point
  • the strength of the metal becomes very weak, and these factors may enable the fabrication of a nanometer-thick metal oxide through a liquid metal squeezing method.
  • the liquid gallium was pressed in a vertical direction using a flat, flat pressing plate.
  • the atomic ratio of the gallium oxide thin film was analyzed using x-ray photoelectron spectroscopy (XPS) (see FIG. 4d ).
  • XPS x-ray photoelectron spectroscopy
  • FIG. 5a is a Raman spectrum of a gallium oxide thin film that was heat-treated at various temperatures before heat treatment (as-fabricated) according to an experimental example
  • FIG. 5b is an x-ray diffraction pattern (XRD) spectrum
  • FIG. 5c is liberation and translation of tetrahedral-octahedra chain and in-plane Ga 2 O 6 peak intensity (peak intensity) of the heat treatment temperature of a g 3 and a g 5 phonon mode (phonon mode) that is associated with the octahedra related optical mode
  • FIG. 5d is the average crystallite size according to the heat treatment temperature.
  • Figure 5a shows the Raman spectrum of the gallium oxide thin film sample according to the heat treatment temperature before (as-fabricated) and heat treatment temperature, the Raman signal (Raman signal) was obtained in a relatively thick portion due to the low scattering yield.
  • Significant phonon mode was not observed in the as-fabricated and heat-treated gallium oxide thin film at 500 ⁇ 650 °C.
  • a phonon mode of beta gallium oxide was observed in the sample heat-treated at 700 ° C. or higher, which is amorphous gallium oxide (amorphous Ga 2 O 3 ) on ⁇ -phase gallium oxide (Ga 2 O 3 ) corresponds to the temperature at which it is converted.
  • the intensity of both Raman modes started to increase after 800°C heat treatment, had the highest value in the sample heat treated at 900°C, and decreased again at a temperature of 950°C or higher was observed.
  • the result of the x-ray diffraction pattern (XRD) shown in FIG. 5B is also consistent with the Raman analysis result.
  • a significant peak was not observed in the sample heat treated up to 650 ° C, but diffraction peaks consistent with the pattern of beta gallium oxide ( ⁇ -Ga 2 O 3 ) were observed in the sample heat treated at a temperature of 700 ° C. or higher.
  • the peak associated with the crystalline gallium oxide (Ga 2 O 3 ) was not observed.
  • the most prominent peak was the (111) beta gallium oxide plane ( ⁇ -Ga 2 O 3 plane), and other plane reflections were also observed.
  • D average crystallite size
  • k 0.9
  • ⁇ the full width at the half maximum in radians
  • ⁇ the Bragg angle of the considered diffraction peak to be.
  • the average grain size of the sample heat treated at 800 °C was observed to increase to 41.3 nm from 36.4 nm to 900 °C heat treatment, and then decreased at a higher temperature to decrease to 37.2 nm after heat treatment at 1000 °C (see Fig. 5d).
  • the average grain size of beta gallium oxide grown at 900°C was determined by spray pyrolysis, electron-beam evaporation, sol-gel, pulsed laser deposition, and sputtering. ) has a larger size than beta gallium oxide grown through At a relatively low temperature, a thin film having a low crystallinity is formed because sufficient energy for ad-atomic migration is not supplied.
  • the optimal temperature at which a 2D gallium oxide thin film obtained from liquid gallium is transformed into a 2D beta gallium oxide thin film was determined to be 900°C, which was previously grown by e-beam evaporation, CVD, etc. is similar to the temperature of
  • Figure 6 shows the characteristics of the 2D beta gallium oxide thin film formed by heat treatment at 900 °C according to the experimental example
  • Figure 6a shows the components of the beta gallium oxide thin film calculated from XPS (x-ray photoelectron spectroscopy) data
  • 6b is a photoluminescence (PL) spectrum of the beta gallium oxide thin film
  • FIG. 6c is an absorbance spectrum of the beta gallium oxide thin film measured using UV-vis absorption spectroscopy
  • FIG. 6d is The valence band maximum (VBM) of the beta gallium oxide thin film is shown
  • FIG. 6e shows the VBM-core delta region and the energy band structure of the beta gallium oxide.
  • VO oxygen vacancy
  • FIG. 6B shows a photoluminescence (PL) spectrum of a beta gallium oxide thin film measured at room temperature using a 325 nm laser as an excitation source.
  • the emission centered at 437 and 527 nm is the gallium-oxygen vacancy pairs (V Ga -V O ) and neutral oxygen interstitials (O i ), respectively.
  • 0 is the result of electron-hole recombination.
  • Figure 6c shows the absorbance spectrum (absorbance spectrum) of the beta gallium oxide thin film measured using UV-vis absorption spectroscopy.
  • the optical band gap (E g ) of a direct band gap material can be calculated from the absorption edge using the following equation.
  • ⁇ the absorption coefficient
  • h ⁇ the photon energy
  • c constant.
  • the optical band gap of 2D beta gallium oxide derived from the Tauc plot as shown in the inset of FIG. 6c is about 5.34 eV
  • the band gap of bulk beta gallium oxide (4.7-4.9) eV) has a larger value. Since the thickness of the 2D beta gallium oxide thin film formed by the squeezing method is about 2-3 nm, which is smaller than the exciton Bohr radius of beta gallium oxide, 3.29 nm, the observed band gap difference is strong quantum This can be explained by the effect of the quantum confinement effect.
  • the band gap of 2D beta gallium oxide enables the formation of an additional beta gallium oxide layer using van der Waals epitaxy, epitaxial growth.
  • the same process may be repeated thereon to additionally form a beta gallium oxide layer.
  • the E g was about 5.18 eV, and a decrease in the optical band gap was observed due to the decrease in the quantum confinement effect. Therefore, like the existing van der Waals two-dimensional materials such as TMD or black phosphorus, the desired thickness or band gap can be adjusted using van der Waals epitaxy according to the application.
  • VBM valence band maximum
  • FIG. 7A is an optical microscope image of a beta gallium oxide thin film grown on a graphene, quartz, Si(100), or sapphire substrate
  • FIG. 7B is an optical microscope image of a beta gallium oxide thin film. Shows the surface roughness (surface topography)
  • Figure 7c is a Raman spectrum (raman spectra) of the beta gallium oxide thin film
  • Figure 7d shows the XRD (x-ray diffraction pattern) spectrum of the beta gallium oxide thin film.
  • beta gallium oxide showed millimeter-scale void-free full coverage, and rms were 0.76, 1.5, 2.2, and 14 nm, respectively.
  • the roughness of the grown nano beta gallium oxide thin film is affected by two factors. The first factor is the roughness of the underlying substrate.
  • the rms of the graphene, quartz, Si, and sapphire substrates were 0.67, 1.5, 0.86, and 9.9 nm, respectively, which is similar to the rms of the beta gallium oxide thin film.
  • the thin film has high roughness despite the low rms of the substrate, which can be explained by the effect of the interface tension.
  • Liquid gallium has low viscosity and high surface energy, but has high wettability to hydrophilic substrates under the influence of surface oxides formed as a result of Cabrera-Mott oxidation. Therefore, even on a Si or Pt substrate with high surface energy, it has dewetting due to high interfacial tension (see FIG. 7b ).
  • the surface energy can be adjusted by methods such as UV/ozone, oxygen plasma, and acid etching, thereby controlling the wettability.
  • a phase change to alpha gallium oxide may occur.
  • the strain is relaxed through a phase change from the twin boundary to the hexagonal-shaped metastable ⁇ phase (refer to FIG. 7e ).
  • a heterophase Ga 2 O 3 in which ⁇ and ⁇ phases are mixed may be formed by a strain of the gallium oxide layer caused by a difference in surface morphology or surface energy of the substrate. Since this metastable alpha gallium oxide has a wider band gap than that of the ⁇ phase, interest is growing as a candidate material for ultra-high breakdown transistors or deep UV opto-electronics at sub-240 nm wavelength.
  • the present invention prepares a beta gallium oxide thin film by transferring and compressing liquid gallium in the form of droplets on a substrate to generate a 2D gallium oxide layer, and forming a 2D beta gallium oxide layer through heat treatment on the gallium oxide layer It is a technology that can be used for industrial purposes.

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Abstract

The present invention relates to a method for fabricating a beta-gallium oxide thin film. A method for fabricating a beta-gallium oxide thin film according to an embodiment of the present invention comprises the steps of: transferring liquid gallium in a droplet form onto a substrate; forming a two-dimensional thin film type of gallium oxide layer by compression of the transferred liquid gallium through a compressing plate; and forming a two-dimensional thin film type of beta-gallium oxide layer by heat treatment of the gallium oxide layer.

Description

베타 산화갈륨 박막 제조방법Beta Gallium Oxide Thin Film Manufacturing Method
본 발명은 베타 산화갈륨 박막을 제조하는 방법에 관한 것으로서, 보다 상세하게는 액상 갈륨을 이용해 베타 산화갈륨 박막을 제조하는 방법에 관한 것이다.The present invention relates to a method for manufacturing a beta gallium oxide thin film, and more particularly, to a method for manufacturing a beta gallium oxide thin film using liquid gallium.
최근 반도체의 집적도가 높아지고 소자의 크기가 점점 작아짐에 따라 누설전류, 채널 길이 변조, 고온 반송자 효과 등의 문제점이 발생하면서 실리콘 반도체 소자의 한계가 나타나고 있다. 또한, 고내압, 고전류, 고온, 고주파수 등의 환경에서 사용되는 반도체 분야에서는 소형화에 따른 이러한 문제점들이 매우 중요하게 작용되면서 새로운 반도체 소재들이 주목받고 있다. 고전력, 고주파 특성을 갖는 반도체 소자를 구현하기 위해서는 높은 항복 전압과 동시에 높은 전자 이동도를 갖는 반도체 소재가 필요한데, 이러한 점에서 SiC, GaN, Ga2O3 등이 적합하다. 그 중에서 Ga2O3은 SiC와 GaN에 비해 상대적으로 더 넓은 에너지 밴드갭을 가지는 소재로서, 융액 성장을 통한 단결정 기판 제작이 가능하여 최근 활발하게 연구 개발이 진행되고 있다. Recently, as the degree of integration of semiconductors increases and the size of devices becomes smaller, problems such as leakage current, channel length modulation, and high-temperature carrier effect occur, and limitations of silicon semiconductor devices appear. In addition, in the field of semiconductors used in environments such as high withstand voltage, high current, high temperature, and high frequency, these problems due to miniaturization become very important, and new semiconductor materials are attracting attention. In order to realize a semiconductor device having high power and high frequency characteristics, a semiconductor material having a high breakdown voltage and high electron mobility is required. In this regard, SiC, GaN, Ga 2 O 3, etc. are suitable. Among them, Ga 2 O 3 is a material having a relatively wider energy bandgap compared to SiC and GaN, and since it is possible to fabricate a single crystal substrate through melt growth, research and development is being actively conducted in recent years.
Ga2O3은 다양한 상으로 존재할 수 있는데, β상이 물리적, 화학적으로 안정하기 때문에 소자의 응용에 가장 적절하다. β-Ga2O3은 높은 기계적, 화학적 안정성을 가지고, 4.9 eV의 에너지 밴드갭을 가지므로 고내압, 저손실 전력 반도체 소재로 유용하고, SiC, GaN보다 3배 더 큰 8 MV/cm의 파괴강도를 갖는 산화물 반도체로서 전력 반도체 시장에서 주목받고 있다. 또한, 그러한 특성으로 인해 β-Ga2O3은 반도체 레이저, 전계효과 트랜지스터, 스위칭 메모리, 고온 가스센서에 적용될 수 있고, UV와 가시광 영역에서 높은 광학적 투과도를 가지므로 Solar-blind UV photodetector 제작에도 활용될 수 있다. Ga 2 O 3 may exist in various phases, and since the β phase is physically and chemically stable, it is most suitable for device applications. β-Ga 2 O 3 has high mechanical and chemical stability and an energy bandgap of 4.9 eV, so it is useful as a high withstand voltage, low loss power semiconductor material. It is attracting attention in the power semiconductor market as an oxide semiconductor with In addition, due to such characteristics, β-Ga 2 O 3 can be applied to semiconductor lasers, field-effect transistors, switching memories, and high-temperature gas sensors. can be
종래 β-Ga2O3 박막의 제조방법으로는 RF-sputtering 증착법, MBE 성장법, MOCVD 성장법, sol-gel process 등이 있다. 그러나 종래 β-Ga2O3 박막 제조방법들에 따르면, 박막을 성장시킬 수 있는 기판이 제한되며, 고진공 공정과 후공정이 필수적이고, 성장 단가가 높다는 문제가 있다. Conventional β-Ga 2 O 3 As a method of manufacturing a thin film, there are RF-sputtering deposition method, MBE growth method, MOCVD growth method, sol-gel process, and the like. However, conventional β-Ga 2 O 3 According to the thin film manufacturing methods, there are problems in that the substrate on which the thin film can be grown is limited, a high vacuum process and a post process are essential, and the growth unit cost is high.
이에 낮은 성장 단가로 대면적의 β-Ga2O3 박막을 제작할 수 있는 기술이 절실히 요구되고 있다. Therefore, β-Ga 2 O 3 of a large area at a low growth unit cost A technology capable of producing a thin film is urgently required.
본 발명은 상술한 종래기술의 문제점을 해결하기 위한 것으로, 본 발명의 일 측면은 기판 상에 액적(droplet) 형태의 액상 갈륨을 전사 및 압착하여 2D 산화갈륨층을 생성하고, 그 산화갈륨층에 대한 열처리를 통해 2D 베타 산화갈륨층을 형성하여, 베타 산화갈륨 박막을 제조하는 베타 산화갈륨 박막 제조방법을 제공하는 데 있다.The present invention is to solve the problems of the prior art described above, and an aspect of the present invention is to transfer and press liquid gallium in the form of droplets on a substrate to generate a 2D gallium oxide layer, and to the gallium oxide layer. An object of the present invention is to provide a method for manufacturing a beta gallium oxide thin film for manufacturing a beta gallium oxide thin film by forming a 2D beta gallium oxide layer through heat treatment.
본 발명의 다른 측면은 형성된 베타 산화갈륨층 상에, 상기 전사, 압착 및 열처리 공정을 반복 수행하여 다층 구조의 베타 산화갈륨 박막을 제조하는 베타 산화갈륨 박막 제조방법을 제공하고자 하는 것이다.Another aspect of the present invention is to provide a method for manufacturing a beta gallium oxide thin film for manufacturing a beta gallium oxide thin film having a multilayer structure by repeatedly performing the transfer, compression and heat treatment processes on the formed beta gallium oxide layer.
본 발명의 실시예에 따른 베타 산화갈륨 박막 제조방법은 (a) 기판 상에, 액적(droplet) 형태로 액상 갈륨을 전사하는 단계; (b) 압착판으로 전사된 상기 액상 갈륨을 압착하여, 2차원 박막 형태의 산화갈륨층을 형성하는 단계; 및 (c) 상기 산화갈륨층을 열처리하여, 2차원 박막 형태의 베타 산화갈륨층을 형성하는 단계;를 포함한다.A beta gallium oxide thin film manufacturing method according to an embodiment of the present invention comprises the steps of (a) transferring liquid gallium on a substrate in the form of droplets; (b) compressing the liquid gallium transferred to a compression plate to form a two-dimensional thin film-type gallium oxide layer; and (c) heat-treating the gallium oxide layer to form a beta gallium oxide layer in the form of a two-dimensional thin film.
또한, 본 발명의 실시예에 따른 베타 산화갈륨 박막 제조방법에 있어서, 상기 (a) 단계는, 마이크로 피펫(micro pipet)을 이용해, 상기 액상 갈륨을 액적 형태로, 상기 기판 상에 떨어뜨리는 단계;를 포함할 수 있다.In addition, in the method for manufacturing a beta gallium oxide thin film according to an embodiment of the present invention, the step (a) includes: using a micro pipet, dropping the liquid gallium in the form of droplets on the substrate; may include
또한, 본 발명의 실시예에 따른 베타 산화갈륨 박막 제조방법에 있어서, 상기 (a) 단계는, 30℃ 이상으로 가열된 핫 플레이트(hot plate) 상에, 상기 기판을 배치하는 단계; 및 상기 기판 상에 상기 액상 갈륨을 떨어뜨리는 단계;를 포함할 수 있다.In addition, in the beta gallium oxide thin film manufacturing method according to an embodiment of the present invention, the step (a) comprises: disposing the substrate on a hot plate heated to 30° C. or higher; and dropping the liquid gallium on the substrate.
또한, 본 발명의 실시예에 따른 베타 산화갈륨 박막 제조방법에 있어서, 상기 (b) 단계에서, 0.5 ~ 50 N의 압착력으로 상기 액상 갈륨을 압착할 수 있다.In addition, in the beta gallium oxide thin film manufacturing method according to an embodiment of the present invention, in the step (b), the liquid gallium may be compressed with a compression force of 0.5 to 50 N.
또한, 본 발명의 실시예에 따른 베타 산화갈륨 박막 제조방법에 있어서, 상기 (b) 단계에서, 압착한 상기 압착판은, 상기 산화갈륨층의 상부면에 대해 수직한 방향으로 이격되면서 제거될 수 있다.In addition, in the beta gallium oxide thin film manufacturing method according to an embodiment of the present invention, in the step (b), the compressed plate may be removed while being spaced apart in a direction perpendicular to the upper surface of the gallium oxide layer. have.
또한, 본 발명의 실시예에 따른 베타 산화갈륨 박막 제조방법에 있어서, 상기 (c) 단계에서, 500 ~ 1000℃의 온도로 열처리할 수 있다.In addition, in the beta gallium oxide thin film manufacturing method according to an embodiment of the present invention, in the step (c), it may be heat-treated at a temperature of 500 ~ 1000 ℃.
또한, 본 발명의 실시예에 따른 베타 산화갈륨 박막 제조방법에 있어서, 상기 (a) 단계에서 전사되는 상기 액상 갈륨의 양, 및 상기 (b) 단계에서 상기 액상 갈륨을 압착하는 압착력에 의해, 상기 베타 산화갈륨 박막의 두께 및 면적이 조절될 수 있다.In addition, in the beta gallium oxide thin film manufacturing method according to an embodiment of the present invention, by the amount of the liquid gallium transferred in step (a), and the compressive force for compressing the liquid gallium in step (b), the The thickness and area of the beta gallium oxide thin film can be controlled.
또한, 본 발명의 실시예에 따른 베타 산화갈륨 박막 제조방법에 있어서, 상기 (c) 단계 이후에, 상기 (c) 단계에서 생성된 상기 베타 산화갈륨층 상에, 상기 (a) 단계에 따른 액상 전사 단계, 상기 (b) 단계에 따른 산화갈륨층 형성 단계, 및 상기 (c) 단계에 따른 베타 산화갈륨층 형성 단계를 순차적으로, n(n≥1, 자연수) 회 추가 수행하여, 상기 기판 상에 n+1(n≥1, 자연수) 개의 상기 베타 산화갈륨층을 적층시킬 수 있다.In addition, in the method for manufacturing a beta gallium oxide thin film according to an embodiment of the present invention, after step (c), on the beta gallium oxide layer generated in step (c), the liquid phase according to step (a) The transfer step, the gallium oxide layer forming step according to the step (b), and the beta gallium oxide layer forming step according to the step (c) are sequentially performed n (n≧1, natural number) times additionally, so that on the substrate n+1 (n≥1, natural number) of the beta gallium oxide layers may be stacked on
본 발명의 특징 및 이점들은 첨부도면에 의거한 다음의 상세한 설명으로 더욱 명백해질 것이다.The features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.
이에 앞서 본 명세서 및 청구범위에 사용된 용어나 단어는 통상적이고 사전적인 의미로 해석되어서는 아니 되며, 발명자가 그 자신의 발명을 가장 최선의 방법으로 설명하기 위해 용어의 개념을 적절하게 정의할 수 있다는 원칙에 입각하여 본 발명의 기술적 사상에 부합하는 의미와 개념으로 해석되어야만 한다.Prior to this, the terms or words used in the present specification and claims should not be construed in a conventional and dictionary meaning, and the inventor may properly define the concept of a term to describe his invention in the best way. Based on the principle that there is, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.
본 발명에 따르면, 기판 상에 액적 형태의 액상 갈륨을 전사 및 압착하여 생성된 2D 산화갈륨층을 열처리하여 2D 베타 산화갈륨 박막을 제조함으로써, 액상 갈륨의 양과 압착 강도에 따라 그 박막의 두께를 나노 내지 마이크로 크기로 조절할 수 있고, 박막의 면적 또한 조절 가능하다.According to the present invention, a 2D beta gallium oxide thin film is manufactured by heat-treating a 2D gallium oxide layer produced by transferring and compressing liquid gallium in the form of droplets on a substrate, thereby reducing the thickness of the thin film according to the amount of liquid gallium and compression strength. It can be adjusted to a micro size, and the area of the thin film can also be adjusted.
또한, 종래 베타 산화갈륨 박막 제조방법(특히, 에피성장법)의 진공 공정이 요구되지 않으므로, 연속 공정이 가능하여 대량으로 베타 산화갈륨 박막을 제조할 수 있고, 기판에 도포된 액상 갈륨층의 산화를 이용하기 때문에 격자 불일치에 의한 효과를 줄일 수 있어서 성장 기판의 자유도가 높다.In addition, conventional beta gallium oxide Since the vacuum process of the thin film manufacturing method (especially the epitaxial growth method) is not required, a continuous process is possible and a beta gallium oxide thin film can be manufactured in large quantities. The degree of freedom of the growth substrate is high because the effect of
결국, 본 발명에 통해 결정성의 베타 산화갈륨 박막을 임의의 기판에 직접 성장할 경우에 공정 시간과 비용이 절감되고, 박막 두께 및 면적 조절을 통해 최적화된 베타 산화갈륨 기반 광학, 전자소자의 제작을 용이하게 할 수 있다.As a result, when a crystalline beta gallium oxide thin film is directly grown on an arbitrary substrate through the present invention, process time and cost are reduced, and the optimized beta gallium oxide-based optical and electronic device can be manufactured through thin film thickness and area control can do it
도 1 내지 도 2는 본 발명의 일 실시예에 따른 베타 산화갈륨 박막 제조방법의 순서도이다.1 to 2 are flowcharts of a method for manufacturing a beta gallium oxide thin film according to an embodiment of the present invention.
도 3은 본 발명의 다른 실시예에 따른 베타 산화갈륨 박막 제조방법의 순서도이다.3 is a flowchart of a method for manufacturing a beta gallium oxide thin film according to another embodiment of the present invention.
도 4a는 실험예에 따른 베타 산화갈륨 박막 제조방법의 순서도이고, 도 4b는 열처리 전 산화갈륨 박막의 현미경 이미지이며, 도 4c는 AFM(atomic force microscope)으로 측정한 산화갈륨 박막의 높이 프로파일(height profile)이고, 도 4d는 XPS(x-ray photoelectron spectroscopy)를 이용한 산화갈륨 박막의 원소비(atomic ratio) 분석 결과이다.4A is a flowchart of a method for manufacturing a beta gallium oxide thin film according to an experimental example, FIG. 4B is a microscope image of the gallium oxide thin film before heat treatment, and FIG. 4C is a height profile of the gallium oxide thin film measured with an atomic force microscope (AFM) profile), and FIG. 4d is an atomic ratio analysis result of the gallium oxide thin film using x-ray photoelectron spectroscopy (XPS).
도 5a는 실험예에 따른 열처리 전(as-fabricated), 및 다양한 온도로 열처리한 산화갈륨 박막의 라만 스펙트럼(raman spectra)이고, 도 5b는 XRD(x-ray diffraction pattern) 스펙트럼이며, 도 5c는 liberation and translation of tetrahedral-octahedra chain과 in-plane Ga2O6 octahedra related optical mode와 연관되는 Ag 3와 Ag 5 포논 모드(phonon mode)의 열처리 온도에 따른 피크 강도(peak intensity)이고, 도 5d는 열처리 온도에 따른 평균 결정립 크기(average crystallite size)이다.5a is a Raman spectrum of a gallium oxide thin film that was heat-treated at various temperatures before heat treatment (as-fabricated) according to an experimental example, and FIG. 5b is an x-ray diffraction pattern (XRD) spectrum, and FIG. 5c is liberation and translation of tetrahedral-octahedra chain and in-plane Ga 2 O 6 peak intensity (peak intensity) of the heat treatment temperature of a g 3 and a g 5 phonon mode (phonon mode) that is associated with the octahedra related optical mode, and FIG. 5d is the average crystallite size according to the heat treatment temperature.
도 6은 실험예에 따른 900℃로 열처리하여 형성한 2D 베타 산화갈륨 박막의 특성을 나타낸 것으로, 도 6a는 XPS(x-ray photoelectron spectroscopy) 데이터로부터 계산된 베타 산화갈륨 박막의 성분을 나타내고, 도 6b는 베타 산화갈륨 박막의 포토루미네선스 스펙트럼(photoluminescence (PL) spectrum)이며, 도 6c는 UV-vis absorption spectroscopy를 이용하여 측정한 베타 산화갈륨 박막의 흡광도 스펙트럼(absorbance spectrum)이고, 도 6d는 베타 산화갈륨 박막의 VBM(valence band maximum)을 나타내며, 도 6e는 베타 산화갈륨의 VBM-core delta 영역과 에너지 밴드 구조를 나타낸다.Figure 6 shows the characteristics of the 2D beta gallium oxide thin film formed by heat treatment at 900 °C according to the experimental example, Figure 6a shows the components of the beta gallium oxide thin film calculated from XPS (x-ray photoelectron spectroscopy) data, 6b is a photoluminescence (PL) spectrum of the beta gallium oxide thin film, FIG. 6c is an absorbance spectrum of the beta gallium oxide thin film measured using UV-vis absorption spectroscopy, and FIG. 6d is The valence band maximum (VBM) of the beta gallium oxide thin film is shown, and FIG. 6e shows the VBM-core delta region and the energy band structure of the beta gallium oxide.
도 7a는 그래핀(graphene), 쿼츠(quartz), Si(100), 사파이어(sapphire) 기판에서 성장된 베타 산화갈륨 박막의 광학 현미경 이미지(optical microscope image)이고, 도 7b는 베타 산화갈륨 박막의 표면 거칠기(surface topography)를 나타내며, 도 7c는 베타 산화갈륨 박막의 라만 스펙트럼(raman spectra)이고, 도 7d는 베타 산화갈륨 박막의 XRD(x-ray diffraction pattern) 스펙트럼을 나타내며, 도 7e는 알파(α) 및 베타(β) 상 산화갈륨의 스트레인(strain)을 나타낸다.7A is an optical microscope image of a beta gallium oxide thin film grown on a graphene, quartz, Si(100), or sapphire substrate, and FIG. 7B is an optical microscope image of a beta gallium oxide thin film. It shows the surface roughness (surface topography), Figure 7c is a Raman spectrum (raman spectra) of the beta gallium oxide thin film, Figure 7d shows the XRD (x-ray diffraction pattern) spectrum of the beta gallium oxide thin film, Figure 7e is an alpha ( The strains of gallium oxide in α) and beta (β) phases are shown.
본 발명의 목적, 특정한 장점들 및 신규 특징들은 첨부된 도면들과 연관되어지는 이하의 상세한 설명과 바람직한 실시예들로부터 더욱 명백해질 것이다. 본 명세서에서 각 도면의 구성요소들에 참조번호를 부가함에 있어서, 동일한 구성 요소들에 한해서는 비록 다른 도면상에 표시되더라도 가능한 한 동일한 번호를 가지도록 하고 있음에 유의하여야 한다. 또한, "제1", "제2" 등의 용어는 하나의 구성요소를 다른 구성요소로부터 구별하기 위해 사용되는 것으로, 구성요소가 상기 용어들에 의해 제한되는 것은 아니다. 이하, 본 발명을 설명함에 있어서, 본 발명의 요지를 불필요하게 흐릴 수 있는 관련된 공지 기술에 대한 상세한 설명은 생략한다.The objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings and preferred embodiments. In the present specification, in adding reference numbers to the components of each drawing, it should be noted that only the same components are given the same number as possible even though they are indicated on different drawings. Also, terms such as “first” and “second” are used to distinguish one component from another, and the component is not limited by the terms. Hereinafter, in describing the present invention, detailed descriptions of related known technologies that may unnecessarily obscure the gist of the present invention will be omitted.
이하, 첨부된 도면을 참조하여 본 발명의 바람직한 실시형태를 상세히 설명하기로 한다.Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
도 1 내지 도 2는 본 발명의 일 실시예에 따른 베타 산화갈륨 박막 제조방법의 순서도이다.1 to 2 are flowcharts of a method for manufacturing a beta gallium oxide thin film according to an embodiment of the present invention.
도 1 내지 도 2에 도시된 바와 같이, 본 발명의 일 실시예에 따른 베타 산화갈륨 박막 제조방법은 기판 상에, 액적(droplet) 형태로 액상 갈륨을 전사하는 단계, 압착판으로 전사된 액상 갈륨을 압착하여, 2차원 박막 형태의 산화갈륨층을 형성하는 단계, 및 산화갈륨층을 열처리하여, 2차원 박막 형태의 베타 산화갈륨층을 형성하는 단계를 포함한다.1 to 2, the beta gallium oxide thin film manufacturing method according to an embodiment of the present invention includes transferring liquid gallium in the form of droplets on a substrate, and transferring liquid gallium to a press plate. By pressing the to form a gallium oxide layer in the form of a two-dimensional thin film, and heat-treating the gallium oxide layer, comprising the steps of forming a beta gallium oxide layer in the form of a two-dimensional thin film.
본 발명은 베타 산화갈륨(β-Ga2O3) 박막을 제조하는 방법에 관한 것이다. 고전력, 고주파 특성을 갖는 반도체 소자를 구현하기 위해서는 높은 항복 전압과 동시에 높은 전자 이동도를 갖는 반도체 소재가 필요한데, 그 중 β-Ga2O3은 높은 기계적, 화학적 안정성을 가지고, 4.9 eV의 에너지 밴드갭을 가지므로 고내압, 저손실 전력 반도체 소재로 유용하고, SiC, GaN보다 3배 더 큰 8 MV/cm의 파괴강도를 갖는 산화물 반도체로서, 전력 반도체, 반도체 레이저, 전계효과 트랜지스터, 스위칭 메모리, 고온 가스센서에 적용될 수 있고, UV와 가시광 영역에서 높은 광학적 투과도를 가지므로 Solar-blind UV photodetector 제작에도 활용될 수 있어서 최근 주목받고 있다. 다만, RF-sputtering 증착법, MBE 성장법, MOCVD 성장법, sol-gel process 등과 같은 종래 β-Ga2O3 박막의 제조방법들은 박막을 성장시킬 수 있는 기판이 제한되며, 고진공 공정과 후공정이 필수적이고, 성장 단가가 높아 β-Ga2O3 박막의 상용화가 어려운 바, 이에 대한 해결방안으로서 본 발명이 안출되었다.The present invention relates to a method for manufacturing a beta gallium oxide (β-Ga 2 O 3 ) thin film. In order to realize a semiconductor device with high power and high frequency characteristics, a semiconductor material having a high breakdown voltage and high electron mobility is required. Among them, β-Ga 2 O 3 has high mechanical and chemical stability and an energy band of 4.9 eV. Because it has a gap, it is useful as a high withstand voltage, low-loss power semiconductor material. It is an oxide semiconductor with a breaking strength of 8 MV/cm, which is three times greater than that of SiC and GaN. Power semiconductor, semiconductor laser, field effect transistor, switching memory, high temperature Since it can be applied to gas sensors and has high optical transmittance in the UV and visible light regions, it can also be used in the manufacture of solar-blind UV photodetectors, attracting attention recently. However, conventional β-Ga 2 O 3 such as RF-sputtering deposition method, MBE growth method, MOCVD growth method, sol-gel process, etc. Thin film manufacturing methods are limited in the substrate on which the thin film can be grown, a high vacuum process and post process are essential, and the growth unit cost is high, so β-Ga 2 O 3 Since the commercialization of the thin film is difficult, the present invention has been devised as a solution to this problem.
구체적으로, 본 발명의 일 실시예에 따른 베타 산화갈륨 제조방법은, 액상 갈륨 전사 단계(S100), 산화갈륨층 형성 단계(S200), 및 베타 산화갈륨층 형성 단계(S300)를 포함한다.Specifically, the beta gallium oxide manufacturing method according to an embodiment of the present invention includes a liquid gallium transfer step (S100), a gallium oxide layer forming step (S200), and a beta gallium oxide layer forming step (S300).
액상 갈륨 전사 단계(S100)는 액상 갈륨(liquid Ga)을 임의의 기판 상에 떨어뜨리는 공정이다. 여기서, 기판은 SiO2, Si, sapphire, quartz, Pt, graphene, GaAs, Cu 등으로 이루어질 수 있지만, 특별한 제한은 없다. 기판은 아세톤/IPA로 세척하여 사용할 수 있다. 갈륨(Ga)의 녹는점은 대략 29℃로 낮기 때문에, 그 녹는점 이상으로 열을 가해 액상으로 만들 수 있다. 여기서, 액상 갈륨을 기판 위에 전사한다. 일례로, 갈륨의 녹는점 이상, 즉 30℃ 이상으로 가열된 핫 플레이트(hot-plate)에 기판을 배치한 다음에, 그 기판에 액상 갈륨을 떨어뜨릴 수 있다. 이때, 전사된 액상 갈륨은 기판 상에서 퍼지지 않고, 액적(droplet) 형태를 유지한다. 또한, 마이크로 피펫(micro pipet)을 이용해, 상기 액상 갈륨을 액적 형태로, 상기 기판 상에 떨어뜨릴 수도 있다. 이러한 액상 갈륨의 양은 베타 산화갈륨 박막의 두께 및 면적에 영향을 미치므로, 그 양에 따라 박막의 두께 및 면적을 조절할 수 있다. The liquid gallium transfer step (S100) is a process of dropping liquid gallium (liquid Ga) onto an arbitrary substrate. Here, the substrate may be made of SiO 2 , Si, sapphire, quartz, Pt, graphene, GaAs, Cu, or the like, but is not particularly limited. The substrate can be washed with acetone/IPA before use. Since the melting point of gallium (Ga) is as low as 29°C, it can be made into a liquid phase by applying heat above the melting point. Here, liquid gallium is transferred onto the substrate. For example, after placing a substrate on a hot-plate heated to a melting point of gallium or higher, that is, 30° C. or higher, liquid gallium may be dropped onto the substrate. At this time, the transferred liquid gallium does not spread on the substrate, but maintains a droplet shape. In addition, the liquid gallium may be dropped on the substrate in the form of droplets using a micro pipet. Since the amount of liquid gallium affects the thickness and area of the beta gallium oxide thin film, the thickness and area of the thin film can be adjusted according to the amount.
산화갈륨층 형성 단계(S200)에서는 전사된 액적 형태의 액상 갈륨을 압착한다. 이때, 압착판을 이용하여 액적 형태의 액상 갈륨에 수직한 방향으로 압착할 수 있다. 여기서, 압착판은 평탄도가 높은 기판을 선택하는 것이 적절하다. 적어도 액상 갈륨과 밀착되는 일면의 평탄도가 높은 것이 바람직하다. In the gallium oxide layer forming step (S200), the liquid gallium in the form of transferred droplets is compressed. At this time, it can be compressed in a direction perpendicular to the liquid gallium in droplet form using a compression plate. Here, it is appropriate to select a substrate having a high flatness for the compression plate. It is preferable that at least one surface in close contact with liquid gallium has a high flatness.
액상 갈륨을 압착하기 위해 압착판에 가해지는 힘인 압착력은 0.5 ~ 50 N일 수 있다. 다만, 그 압착력의 범위가 반드시 상기와 같이 한정되는 것은 아니고, 액상 갈륨에 가해지는 압착력에 따라 베타 산화갈륨 박막의 두께 및 면적이 결정되므로, 이를 고려하여 압착력의 범위가 정해질 수 있다. 이에 의해 베타 산화갈륨 박막의 두께는 수 ㎚에서 수 ㎛로 조절될 수 있다. The compression force, which is the force applied to the pressing plate to compress the liquid gallium, may be 0.5 to 50 N. However, the range of the compression force is not necessarily limited as described above, and since the thickness and area of the beta gallium oxide thin film are determined according to the compression force applied to the liquid gallium, the range of the compression force may be determined in consideration of this. Thereby, the thickness of the beta gallium oxide thin film can be controlled from several nm to several μm.
이렇게 액상 갈륨을 압착하고 난 후, 압착판을 분리함으로써, 박막 형태의 산화갈륨층이 형성된다. 여기서, 액상 갈륨은 압착하는 동안에 산화되어, 종국적으로 2차원 박막 형태의 산화갈륨층이 형성된다. 한편, 압착판을 분리할 때에, 산화갈륨층의 상부면과 슬립(slip)이 발생하지 않도록, 그 상부면에 대해 수직한 방향으로 이격시켜 제거하는 것이 바람직하다.After pressing the liquid gallium in this way, by separating the pressing plate, the gallium oxide layer in the form of a thin film is formed. Here, the liquid gallium is oxidized during compression, and ultimately a two-dimensional thin film-type gallium oxide layer is formed. On the other hand, when separating the compression plate, it is preferable to remove the upper surface of the gallium oxide layer and spaced apart in a direction perpendicular to the upper surface so that slip (slip) does not occur.
베타 산화갈륨층 형성 단계(S300)는 산화갈륨층에 대해 열처리를 수행하는 공정이다. 여기서, 열처리를 통해 2차원 박막 형태의 베타 산화갈륨층을 생성할 수 있다. 열처리는 산화갈륨층을 β 상으로 만드는 공정으로서, 열처리의 온도와 시간에 따라 산화갈륨층의 상과 결정성이 조절될 수 있다. 이러한 열처리는 상압 및 공기 중에서 진행될 수 있다. 여기서, 열처리 온도는 500 ~ 1000℃가 적합하다. 일례로, 대기 중에서 750℃ 이상에서 30분간의 열처리를 실행함으로써, 베타 산화갈륨층을 생성할 수 있다. 이러한 열처리 공정을 통해 생성된 베타 산화갈륨층으로써, 단층 구조의 베타 산화갈륨 박막이 형성된다.The beta gallium oxide layer forming step (S300) is a process of performing heat treatment on the gallium oxide layer. Here, it is possible to generate a beta gallium oxide layer in the form of a two-dimensional thin film through heat treatment. The heat treatment is a process for making the gallium oxide layer into a β phase, and the phase and crystallinity of the gallium oxide layer can be controlled according to the temperature and time of the heat treatment. Such heat treatment may be performed at normal pressure and in air. Here, the heat treatment temperature is preferably 500 ~ 1000 ℃. For example, by performing a heat treatment for 30 minutes at 750 ° C. or higher in the atmosphere, a beta gallium oxide layer can be produced. As the beta gallium oxide layer generated through this heat treatment process, a beta gallium oxide thin film having a single layer structure is formed.
종합적으로, 본 발명에 따르면, 본 발명에 따르면, 기판 상에 액적 형태의 액상 갈륨을 전사 및 압착하여 생성된 2D 산화갈륨층을 열처리하여 2D 베타 산화갈륨 박막을 제조함으로써, 액상 갈륨의 양과 압착 강도에 따라 그 박막의 두께를 나노 내지 마이크로 크기로 조절할 수 있고, 박막의 면적 또한 조절 가능하다. 또한, 종래 베타 산화갈륨 박막 제조방법(특히, 에피성장법)의 진공 공정이 요구되지 않으므로, 연속 공정이 가능하여 대량으로 베타 산화갈륨 박막을 제조할 수 있고, 기판에 도포된 액상 갈륨층의 산화를 이용하기 때문에 격자 불일치에 의한 효과를 줄일 수 있어서 성장 기판의 자유도가 높다. 결국, 본 발명에 통해 결정성의 베타 산화갈륨 박막을 임의의 기판에 직접 성장할 경우에 공정 시간과 비용이 절감되고, 박막 두께 및 면적 조절을 통해 최적화된 베타 산화갈륨 기반 광학, 전자소자의 제작을 용이하게 할 수 있다.Overall, according to the present invention, the amount of liquid gallium and compressive strength are obtained by manufacturing a 2D beta gallium oxide thin film by heat-treating a 2D gallium oxide layer produced by transferring and compressing liquid gallium in the form of droplets on a substrate. The thickness of the thin film can be adjusted to a nano to micro size according to the thickness of the thin film, and the area of the thin film can also be adjusted. In addition, conventional beta gallium oxide Since the vacuum process of the thin film manufacturing method (especially the epitaxial growth method) is not required, a continuous process is possible and a beta gallium oxide thin film can be manufactured in large quantities. The degree of freedom of the growth substrate is high because the effect of As a result, when a crystalline beta gallium oxide thin film is directly grown on an arbitrary substrate through the present invention, process time and cost are reduced, and the optimized beta gallium oxide-based optical and electronic device can be manufactured through thin film thickness and area control can do it
도 3은 본 발명의 다른 실시예에 따른 베타 산화갈륨 박막 제조방법의 순서도이다.3 is a flowchart of a method for manufacturing a beta gallium oxide thin film according to another embodiment of the present invention.
도 3을 참고로, 본 발명의 다른 실시예에 따른 베타 산화갈륨 박막 제조방법은 다층 구조의 베타 산화갈륨 박막을 형성하는 것으로서, 상기 일 실시예의 열처리를 통해 단층 베타 산화갈륨층(이하, 제1 베타 산화갈륨층이라 함)을 생성하고 난 다음, 그 제1 베타 산화갈륨층 상에 액적 형태로 액상 갈륨 전사하고 압착하여 제2 산화갈륨층을 생성하고, 다시 열처리를 수행하여 제2 베타 산화갈륨층을 형성할 수 있다.3, the beta gallium oxide thin film manufacturing method according to another embodiment of the present invention is to form a beta gallium oxide thin film having a multi-layer structure, and a single-layer beta gallium oxide layer (hereinafter, the first After forming a beta gallium oxide layer), liquid gallium is transferred in the form of droplets on the first beta gallium oxide layer and compressed to form a second gallium oxide layer, and heat treatment is performed again to perform second beta gallium oxide layer can be formed.
즉, 상기 일 실시예에 따라 기판에 베타 산화갈륨층을 형성하여 기판/(베타 산화갈륨층)1을 제조하고, 그 위에 액상 갈륨 전사 단계(S100), 산화갈륨층 형성 단계(S200), 및 베타 산화갈륨층 형성 단계(S300)를 순차적으로 n(n은 1 이상의 자연수)회 수행함으로써, 기판 상에 n+1(n은 1 이상의 자연수) 개의 상기 베타 산화갈륨층을 순차적으로 적층함으로써, 다층 구조의 베타 산화갈륨 박막 기판/(베타 산화갈륨층)n+1을 제조할 수 있다.That is, according to the embodiment, a beta gallium oxide layer is formed on the substrate to prepare a substrate/(beta gallium oxide layer) 1 , and a liquid gallium transfer step (S100), a gallium oxide layer forming step (S200), and By sequentially performing the beta gallium oxide layer forming step (S300) n times (n is a natural number greater than or equal to 1), sequentially stacking n+1 (n is a natural number greater than or equal to 1) number of the beta gallium oxide layers on a substrate, A beta gallium oxide thin film substrate/(beta gallium oxide layer) n+1 of the structure can be prepared.
물질의 밴드갭은 두께가 얇아질수록 양자구속(quantum confinement) 효과로 인해, 증가하는 경향이 있다. 이에 상기와 같이 다층 구조의 베타 산화갈륨 박막을 제조하여 그 두께를 조절함으로써, 밴드갭을 벌크(bulk) 베타 산화갈륨의 밴드갭 이상으로 증가시킬 수 있다.The bandgap of a material tends to increase with decreasing thickness, due to the effect of quantum confinement. Accordingly, by controlling the thickness of the beta gallium oxide thin film having a multilayer structure as described above, the band gap can be increased to be higher than that of the bulk beta gallium oxide.
이하에서는 실험예를 통해 본 발명을 보다 상세하게 설명한다.Hereinafter, the present invention will be described in more detail through experimental examples.
1. 실험예1. Experimental example
1.1 압착(squeezing) 방법을 이용한 베타 산화갈륨 박막의 제조1.1 Preparation of Beta Gallium Oxide Thin Film Using Squeezing Method
75℃의 핫 플레이트(hot plate)에 기판을 위치시키고, 그 기판 위에 마이크로 피펫을 이용하여 수 mg의 액상 갈륨 금속 (99.9999% purity, GalliumLab)을 떨어뜨렸다. 그 다음 평평한 면을 가진 압착판을 기판에 수직에 수직하게 20 ~ 50 N의 힘으로 액상 갈륨을 압착하고, 압착판에 슬립(slip)이 발생하지 않도록 수직 방향으로 제거하여 2차원 산화갈륨 박막 샘플을 형성했다. The substrate was placed on a hot plate at 75° C., and several mg of liquid gallium metal (99.9999% purity, GalliumLab) was dropped onto the substrate using a micropipette. Then, a two-dimensional gallium oxide thin film sample was pressed by pressing the liquid gallium with a force of 20 to 50 N perpendicular to the substrate with a press plate with a flat surface, and removing it in the vertical direction so as not to cause slip on the press plate. has formed
그 후에 샘플을 대기 조건에서 tube furnace (Lindberg/Blue M)을 이용하여 500 ~ 1000 ℃로 두 시간 동안 열처리를 진행하였다. 열처리 후 샘플을 65℃의 에탄올에 담그고 부드럽게 러빙(rubbing)하여 잔여 갈륨을 제거하였다. After that, the sample was heat-treated at 500 ~ 1000 °C for two hours using a tube furnace (Lindberg/Blue M) under atmospheric conditions. After heat treatment, the sample was immersed in ethanol at 65° C. and gently rubbed to remove residual gallium.
여기서, graphene, quartz, sapphire, Si 기판을 각각 사용하여 동일하게 실험을 진행하였다.Here, the same experiment was performed using graphene, quartz, sapphire, and Si substrates, respectively.
1.2 분석 방법1.2 Analysis method
산화갈륨 박막의 원소 조성은 X-ray photoelectron spectroscopy (PHI 5000 VersaProbe, ULVAC PHI) with monochromatized Al Kα x-ray source를 이용하여 분석하였다. 베타 산화갈륨 박막의 광학 특성(optical properties)은 광학 현미경 (BX51M, Olympus), UV-vis absorption spectroscope (Lambda 35, PerkinElmer), micro-Raman spectroscopy with 532 nm diode-pumped solid-state laser (Omicron) in a back-scattering geometry, 그리고 photoluminescence (PL) spectroscopy with 325 nm He-Cd laser (Kimmon Koha Co.) as an excitation source로 이용하여 측정하였다. 베타 산화갈륨 박막의 두께와 표면 모폴리지(surface morphology)는 atomic force microscope (AFM)을 이용하여 탭핑 모드(tapping mode)로 분석하였다. 베타 산화갈륨 박막의 결정도(crystallinity)는 X-ray diffraction (XRD, D8 Discover, Bruker) with Cu-Kα radiation으로 분석하였다. The elemental composition of the gallium oxide thin film was analyzed using X-ray photoelectron spectroscopy (PHI 5000 VersaProbe, ULVAC PHI) with monochromatized Al Kα x-ray source. The optical properties of the beta gallium oxide thin film were analyzed under an optical microscope (BX51M, Olympus), UV-vis absorption spectroscope (Lambda 35, PerkinElmer), micro-Raman spectroscopy with 532 nm diode-pumped solid-state laser (Omicron) in It was measured using a back-scattering geometry, and photoluminescence (PL) spectroscopy with 325 nm He-Cd laser (Kimmon Koha Co.) as an excitation source. The thickness and surface morphology of the beta gallium oxide thin film were analyzed in tapping mode using an atomic force microscope (AFM). The crystallinity of the beta gallium oxide thin film was analyzed by X-ray diffraction (XRD, D8 Discover, Bruker) with Cu-Kα radiation.
2. 실험 결과2. Experimental results
2.1 2차원 베타 산화갈륨 박막 제조2.1 Two-dimensional Beta Gallium Oxide Thin Film Manufacturing
도 4a는 실험예에 따른 베타 산화갈륨 박막 제조방법의 순서도이고, 도 4b는 열처리 전 산화갈륨 박막의 현미경 이미지이며, 도 4c는 AFM(atomic force microscope)으로 측정한 산화갈륨 박막의 높이 프로파일(height profile)이고, 도 4d는 XPS(x-ray photoelectron spectroscopy)를 이용한 산화갈륨 박막의 원소비(atomic ratio) 분석 결과이다.4A is a flowchart of a method for manufacturing a beta gallium oxide thin film according to an experimental example, FIG. 4B is a microscope image of the gallium oxide thin film before heat treatment, and FIG. 4C is a height profile of the gallium oxide thin film measured with an atomic force microscope (AFM) profile), and FIG. 4d is an atomic ratio analysis result of the gallium oxide thin film using x-ray photoelectron spectroscopy (XPS).
도 4a와 같이, 실험예에 따른 베타 산화갈륨 박막은 액상 갈륨의 압착(squeezing) 및 열처리(thermal annealing) 등의 2단계를 거쳐 얻어진다. 녹는점이 낮은 금속들(Ga, In, Sn 등)은 공기 중에서 Cabrera-Mott kinetics에 의한 self-limiting oxidation이 쉽게 발생한다. 또한, 녹는점 이상의 온도에서는 금속의 강도가 매우 약해지게 되는데, 이러한 요소들은 액상 금속 압착(liquid metal squeezing) 방법을 통해 나노미터 두께의 금속산화물의 제작을 가능하게 할 수 있다. 75℃의 핫 플레이트(hot plate)에 위치한 기판 (표면이 평평함)에 수 mg의 갈륨 액적(droplet)을 떨어트린 후, 평평하고 표면을 가진 압착판을 이용하여 수직 방향으로 액상 갈륨을 압착하였다. 이후 슬립(slip)이 발생하지 않도록 압착판을 수직 방향으로 제거하고 난 후, 크랙(crack)이나 어그리게이션(aggregation)이 없이 밀리미터 스케일의 균질한 박막이 형성된 것이 관찰되었다(도 4b 참조). 그 두께는 약 3 ㎚로 측정되었다(도 4c 참조). 액상 갈륨은 20 ~ 50 N의 힘으로 균일하게 압착되었는데, 이 범위에서 2 ~ 3.2 nm 두께의 산화갈륨 박막이 형성되었다. 또한, 산화갈륨 박막의 rms(root mean square)는 약 7.7 Å, SiO2 기판의 rms는 약 7.0 Å이었는데, 이는 압착 방법을 통해 형성되는 산화갈륨 박막의 거칠기(roughness)가 압착하는 기판에 지배적으로 영향을 받는 것을 보여준다. 따라서 패터닝 된 기판을 압착 기판으로 이용할 경우 산화갈륨 박막의 두께나 형태를 제어 가능할 것으로 기대된다. As shown in Fig. 4a, the beta gallium oxide thin film according to the experimental example is obtained through two steps, such as squeezing and thermal annealing of liquid gallium. Metals with low melting points (Ga, In, Sn, etc.) easily undergo self-limiting oxidation by Cabrera-Mott kinetics in air. In addition, at a temperature above the melting point, the strength of the metal becomes very weak, and these factors may enable the fabrication of a nanometer-thick metal oxide through a liquid metal squeezing method. After dropping several mg of gallium droplets on a substrate (flat surface) placed on a hot plate at 75° C., the liquid gallium was pressed in a vertical direction using a flat, flat pressing plate. After the compression plate was removed in the vertical direction to prevent slip from occurring, it was observed that a homogeneous thin film of millimeter scale was formed without cracks or aggregation (see FIG. 4b ). Its thickness was measured to be about 3 nm (see Fig. 4c). Liquid gallium was uniformly compressed with a force of 20 to 50 N, and a gallium oxide thin film with a thickness of 2 to 3.2 nm was formed in this range. In addition, the rms (root mean square) of the gallium oxide thin film was about 7.7 Å, and the rms of the SiO 2 substrate was about 7.0 Å, which is the roughness of the gallium oxide thin film formed through the compression method. show that they are affected. Therefore, when the patterned substrate is used as a compression substrate, it is expected that the thickness or shape of the gallium oxide thin film can be controlled.
산화갈륨 박막의 atomic ratio는 x-ray photoelectron spectroscopy (XPS)를 이용하여 분석하였다(도 4d 참조). O 1s와 Ga 2p3 /2 피크의 면적과 relative sensitivity factor을 이용하여 계산된 박막의 stoichiometric ratio는 Ga : O = 1 : 0.6으로 관찰되었다. 이는 자연 산화(natural oxidation)에 의해 공기 중에서 액상 갈륨이 산화되어 gallium (I) oxide (Ga2O) 혹은 불완전 산화(incomplete oxidation)에 의한 gallium (I) oxide와 gallium (III) oxide의 혼합체(mixture)가 형성된 것으로 설명할 수 있다. 결과적으로, Cabrera-Mott oxidation의 빠른 ㅅ사산화 속도(oxidation rate)에 의해 공기 중에서 액상 갈륨은 압착 과정에서 균일하고, 대면적의 나노미터 두께의 산화갈륨 박막을 형성하게 된다. The atomic ratio of the gallium oxide thin film was analyzed using x-ray photoelectron spectroscopy (XPS) (see FIG. 4d ). The stoichiometric ratio of the thin film calculated using the O 1s and Ga 2p 3 /2 peak areas and the relative sensitivity factor was observed to be Ga : O = 1 : 0.6. It is a mixture of gallium (I) oxide (Ga 2 O) or gallium (I) oxide and gallium (III) oxide by incomplete oxidation as liquid gallium is oxidized in air by natural oxidation. ) can be explained by the formation of As a result, due to the rapid oxidation rate of Cabrera-Mott oxidation, liquid gallium in air forms a uniform, large-area, nanometer-thick gallium oxide thin film during the compression process.
위의 나노미터 두께의 산화갈륨 박막으로부터 베타 산화갈륨 박막을 얻기 위하여, 대기 조건에서 열처리를 진행하였다.In order to obtain a beta gallium oxide thin film from the above nanometer-thick gallium oxide thin film, heat treatment was performed under atmospheric conditions.
도 5a는 실험예에 따른 열처리 전(as-fabricated), 및 다양한 온도로 열처리한 산화갈륨 박막의 라만 스펙트럼(raman spectra)이고, 도 5b는 XRD(x-ray diffraction pattern) 스펙트럼이며, 도 5c는 liberation and translation of tetrahedral-octahedra chain과 in-plane Ga2O6 octahedra related optical mode와 연관되는 Ag 3와 Ag 5 포논 모드(phonon mode)의 열처리 온도에 따른 피크 강도(peak intensity)이고, 도 5d는 열처리 온도에 따른 평균 결정립 크기(average crystallite size)이다.5a is a Raman spectrum of a gallium oxide thin film that was heat-treated at various temperatures before heat treatment (as-fabricated) according to an experimental example, and FIG. 5b is an x-ray diffraction pattern (XRD) spectrum, and FIG. 5c is liberation and translation of tetrahedral-octahedra chain and in-plane Ga 2 O 6 peak intensity (peak intensity) of the heat treatment temperature of a g 3 and a g 5 phonon mode (phonon mode) that is associated with the octahedra related optical mode, and FIG. 5d is the average crystallite size according to the heat treatment temperature.
도 5a는 열처리 전(as-fabricated)와 열처리 온도에 따른 산화갈륨 박막 샘플의 라만 스펙트럼을 나타내는데, 라만 신호(Raman signal)는 낮은 scattering yield 때문에 상대적으로 두꺼운 부분에서 얻어졌다. As-fabricated와 500 ~ 650℃까지 열처리한 산화갈륨 박막에서는 유의미한 포논 모드(phonon mode)가 관찰되지 않았다. 하지만, 700℃ 이상에서 열처리한 샘플에서 베타 산화갈륨의 포논 모드(phonon mode)가 관찰되었는데, 이는 상 다이어그램(phase diagram) 상에서 비결정성 산화갈륨(amorphous Ga2O3)를 β상의 산화갈륨(Ga2O3)로 변환시키는 온도와 일치한다. 도 5c를 참고하면, 두 라만 모드의 강도(intensity)는 모두 800℃ 열처리 이후 증가하기 시작하여 900℃로 열처리 한 샘플에서 가장 높은 값을 가지고, 950℃ 이상의 온도에서 다시 감소하는 결과가 관찰되었다. Figure 5a shows the Raman spectrum of the gallium oxide thin film sample according to the heat treatment temperature before (as-fabricated) and heat treatment temperature, the Raman signal (Raman signal) was obtained in a relatively thick portion due to the low scattering yield. Significant phonon mode was not observed in the as-fabricated and heat-treated gallium oxide thin film at 500 ~ 650 °C. However, a phonon mode of beta gallium oxide was observed in the sample heat-treated at 700 ° C. or higher, which is amorphous gallium oxide (amorphous Ga 2 O 3 ) on β-phase gallium oxide (Ga 2 O 3 ) corresponds to the temperature at which it is converted. Referring to FIG. 5C , the intensity of both Raman modes started to increase after 800°C heat treatment, had the highest value in the sample heat treated at 900°C, and decreased again at a temperature of 950°C or higher was observed.
도 5b에 보이는 x-ray diffraction pattern (XRD)의 결과 또한 라만 분석 결과와 일치한다. 650℃까지 열처리한 샘플에서는 유의미한 피크가 관찰되지 않았지만, 700℃ 이상의 온도에서 열처리한 샘플에서 베타 산화갈륨(β-Ga2O3)의 패턴과 일치하는 회절 피크(diffraction peak)들이 관찰되었고, 다른 결정상의 산화갈륨(Ga2O3)에 연관된 피크는 관찰되지 않았다. 800℃ 이상의 모든 열처리 온도에서 가장 두드러진 피크는 (111) 베타 산화갈륨 면(β-Ga2O3 plane)이었고, 다른 면 ㅂ반사(plane reflections)들 또한 관찰되었다. 이러한 라만과 XRD 결과는 액상 갈륨의 압착(squeezing)과 700℃ 이상에서의 후속 열처리(annealing)에 의하여 단일 상(single-phase)의 단사정계 베타 산화갈륨(monoclinic β-Ga2O3)이 형성되었음을 보여준다. 베타 산화갈륨의 평균 결정립 크기(average crystallite size)는 가장 두드러진 (111) 방향 회절 피크((111) orientation diffraction peak)로부터 아래의 쉘러 식(Scherrer's equation)을 이용하여 계산하였다. The result of the x-ray diffraction pattern (XRD) shown in FIG. 5B is also consistent with the Raman analysis result. A significant peak was not observed in the sample heat treated up to 650 ° C, but diffraction peaks consistent with the pattern of beta gallium oxide (β-Ga 2 O 3 ) were observed in the sample heat treated at a temperature of 700 ° C. or higher. The peak associated with the crystalline gallium oxide (Ga 2 O 3 ) was not observed. At all annealing temperatures above 800 °C, the most prominent peak was the (111) beta gallium oxide plane (β-Ga 2 O 3 plane), and other plane reflections were also observed. These Raman and XRD results show that a single-phase monoclinic beta gallium oxide (monoclinic β-Ga 2 O 3 ) is formed by squeezing liquid gallium and subsequent annealing at 700° C. or higher. show that it has been The average crystallite size of beta gallium oxide was calculated using the Scherrer's equation below from the most prominent (111) orientation diffraction peak ((111) orientation diffraction peak).
Figure PCTKR2021006391-appb-img-000001
Figure PCTKR2021006391-appb-img-000001
여기서, D = average crystallite size, k = 0.9, λ = the wavelength of the x-ray radiation(=1.54056 Å), β = the full width at the half maximum in radians, θ = the Bragg angle of the considered diffraction peak이다.where D = average crystallite size, k = 0.9, λ = the wavelength of the x-ray radiation(=1.54056 Å), β = the full width at the half maximum in radians, θ = the Bragg angle of the considered diffraction peak to be.
800℃로 열처리한 샘플의 평균 결정립 크기는 36.4 nm에서 900℃ 열처리까지 41.3 nm로 증가하였다가 그 이상의 온도에서 감소하여 1000℃ 열처리 후 37.2 nm로 감소하는 결과가 관찰되었다(도 5d 참조). 900℃에서 성장한 베타 산화갈륨의 평균 결정립 크기는 분무 열분해(spray pyrolysis), 원자빔 증착(electron-beam evaporation), 졸-겔(sol-gel), 펄스 레이저 증착(pulsed laser deposition), 스퍼터링(sputtering)을 통해 성장시킨 베타 산화갈륨에 비해 더 큰 사이즈를 갖는다. 상대적으로 낮은 온도에서는 ad-atomic migration을 발생시키기 위한 충분한 에너지가 공급되지 못하기 때문에 낮은 결정화도를 갖는 박막이 형성된다. 온도가 700℃ 이상으로 올라가면, 표면의 원자들은 충분한 운동 에너지와 표면 이동도(surface mobility)를 얻게 되어 격자(lattice)의 재구성(reconstruction)이 발생하게 되는데, 이 과정에서 견고한 Ga-O 본드(bond)의 형성으로 결정화도가 향상된다. 하지만 950℃ 이상의 높은 온도에서는 atomic migration이 너무 빠르게 발생하게 되고, 레귤러 본드(regular bond)의 형성 대신 β-Ga2O3의 본드(bond)가 스플리팅(splitting) 되어 결함(defect)이 형성되기 시작한다. 도 5d에 보이는 950℃ 이상에서의 평균 결정립 크기의 감소와 회절 피크의 쉬프트(shift)는 이러한 결함 형성과 그로 인한 스트레인(strain)의 형성에 따른 격자 변형(lattice deformation)으로 설명할 수 있다. 따라서, 액상 갈륨으로부터 얻어진 2D 산화갈륨 박막이 2D 베타 산화갈륨 박막으로 변형되는 최적의 온도는 900℃로 결정되었는데, 이는 기존에 원자빔 증착(e-beam evaporation), CVD 등으로 성장시킨 베타 산화갈륨의 온도와 비슷하다. The average grain size of the sample heat treated at 800 °C was observed to increase to 41.3 nm from 36.4 nm to 900 °C heat treatment, and then decreased at a higher temperature to decrease to 37.2 nm after heat treatment at 1000 °C (see Fig. 5d). The average grain size of beta gallium oxide grown at 900°C was determined by spray pyrolysis, electron-beam evaporation, sol-gel, pulsed laser deposition, and sputtering. ) has a larger size than beta gallium oxide grown through At a relatively low temperature, a thin film having a low crystallinity is formed because sufficient energy for ad-atomic migration is not supplied. When the temperature rises above 700 °C, the atoms on the surface acquire sufficient kinetic energy and surface mobility to cause the reconstruction of the lattice. ), the crystallinity is improved. However, at a high temperature of 950° C. or higher, atomic migration occurs too quickly, and instead of forming a regular bond, a bond of β-Ga 2 O 3 is split and a defect is formed. starts to become The decrease in the average grain size and the shift of the diffraction peak at 950° C. or higher shown in FIG. 5D can be explained by lattice deformation according to the formation of such defects and the resulting strain. Therefore, the optimal temperature at which a 2D gallium oxide thin film obtained from liquid gallium is transformed into a 2D beta gallium oxide thin film was determined to be 900°C, which was previously grown by e-beam evaporation, CVD, etc. is similar to the temperature of
2.2 2차원 베타 산화갈륨 박막의 특성2.2 Characteristics of 2D Beta Gallium Oxide Thin Film
도 6은 실험예에 따른 900℃로 열처리하여 형성한 2D 베타 산화갈륨 박막의 특성을 나타낸 것으로, 도 6a는 XPS(x-ray photoelectron spectroscopy) 데이터로부터 계산된 베타 산화갈륨 박막의 성분을 나타내고, 도 6b는 베타 산화갈륨 박막의 포토루미네선스 스펙트럼(photoluminescence (PL) spectrum)이며, 도 6c는 UV-vis absorption spectroscopy를 이용하여 측정한 베타 산화갈륨 박막의 흡광도 스펙트럼(absorbance spectrum)이고, 도 6d는 베타 산화갈륨 박막의 VBM(valence band maximum)을 나타내며, 도 6e는 베타 산화갈륨의 VBM-core delta 영역과 에너지 밴드 구조를 나타낸다.Figure 6 shows the characteristics of the 2D beta gallium oxide thin film formed by heat treatment at 900 °C according to the experimental example, Figure 6a shows the components of the beta gallium oxide thin film calculated from XPS (x-ray photoelectron spectroscopy) data, 6b is a photoluminescence (PL) spectrum of the beta gallium oxide thin film, FIG. 6c is an absorbance spectrum of the beta gallium oxide thin film measured using UV-vis absorption spectroscopy, and FIG. 6d is The valence band maximum (VBM) of the beta gallium oxide thin film is shown, and FIG. 6e shows the VBM-core delta region and the energy band structure of the beta gallium oxide.
도 6a의 XPS 데이터(data)로부터 계산된 베타 산화갈륨 박막의 원자 조성은 산화갈륨(Ga2O3)의 stoichiometric ratio와 유사한 Ga : O = 1 : 1.67로 관찰되었는데, 이는 건조 공기(dry air) 분위기에서 900℃의 열처리에 의한 산화갈륨 박막의 완벽한 산화를 나타낸다. 또한 O 1s core level의 XPS 피크는 열처리 후 더 높은 결합 에너지(binding energy)에서 관찰되었는데, 이는 추가적인 산화에 의한 산소 공핍 농도(oxygen vacancy (VO) concentration)의 감소를 보여준다. The atomic composition of the beta gallium oxide thin film calculated from the XPS data of FIG. 6a was observed to be Ga: O = 1: 1.67, which is similar to the stoichiometric ratio of gallium oxide (Ga 2 O 3 ), which is dry air. It shows the complete oxidation of the gallium oxide thin film by heat treatment at 900°C in the atmosphere. In addition, the XPS peak of the O 1s core level was observed at higher binding energy after heat treatment, indicating a decrease in oxygen vacancy (VO ) concentration due to additional oxidation.
도 6b는 325 nm 레이저를 여기원(excitation source)으로 이용하여 상온에서 측정한 베타 산화갈륨 박막의 포토루미네선스 스펙트럼(photoluminescence (PL) spectrum)을 나타낸다. 여기서, 437과 527 nm를 중심(center)에 둔 이미션(emission)은 각각 갈륨 산소 공핍 쌍(gallium-oxygen vacancy pairs) (VGa-VO)와 중립 산소 간극(neutral oxygen interstitials) (Oi 0)에 의한 전자-정공 재결합(electron-hole recombination)의 결과이다. 6B shows a photoluminescence (PL) spectrum of a beta gallium oxide thin film measured at room temperature using a 325 nm laser as an excitation source. Here, the emission centered at 437 and 527 nm is the gallium-oxygen vacancy pairs (V Ga -V O ) and neutral oxygen interstitials (O i ), respectively. 0 ) is the result of electron-hole recombination.
도 6c는 UV-vis absorption spectroscopy를 이용하여 측정한 베타 산화갈륨 박막의 흡광도 스펙트럼(absorbance spectrum)을 나타낸다. 직접 밴드 갭(direct band gap) 물질의 광학적 밴드 갭(optical band gap) (Eg)은 다음의 식을 이용하여 흡수단(absorption edge)으로부터 계산될 수 있다. Figure 6c shows the absorbance spectrum (absorbance spectrum) of the beta gallium oxide thin film measured using UV-vis absorption spectroscopy. The optical band gap (E g ) of a direct band gap material can be calculated from the absorption edge using the following equation.
Figure PCTKR2021006391-appb-img-000002
Figure PCTKR2021006391-appb-img-000002
여기서, α = the absorption coefficient, hυ = the photon energy, c = constant이다. 도 6c의 삽입(inset)과 같이 타우 플롯(Tauc plot)으로부터 도출된 2D 베타 산화갈륨의 광학적 밴드 갭(optical band gap)은 약 5.34 eV로 벌크(bulk) 베타 산화갈륨의 밴드 갭(4.7-4.9 eV)에 비해 더 큰 값을 갖는다. 압착(squeezing) 방법에 의해서 형성되는 2D 베타 산화갈륨 박막의 두께는 약 2-3 nm로 베타 산화갈륨의 엑시톤 보어 반경(exciton Bohr radius)인 3.29 nm 보다 작기 때문에 관찰된 밴드 갭의 차이는 강한 양자 제한(quantum confinement) 효과에 의한 영향으로 설명할 수 있다. 뿐만 아니라 2D 베타 산화갈륨의 밴드 갭은 반데르 발스 에피택시(van der Waals epitaxy)를 이용한 추가적인 베타 산화갈륨층의 형성, 에피텍셜 성장(epitaxial growth)를 가능하게 한다. 도 3과 같이 압착과 열처리를 통한 첫 번째 베타 산화갈륨층을 형성하고 나서, 그 위에 같은 공정을 반복하여 베타 산화갈륨층을 추가적으로 형성할 수 있다. 2 nm 두께의 베타 산화갈륨층 위에 3.2 nm의 추가 베타 산화갈륨층을 형성하고 난 후의 Eg는 약 5.18 eV로 양자 제한(quantum confinement) 효과의 감소로 인한 광학적 밴드 갭의 감소가 관찰되었다. 따라서 기존의 TMD나 흑린(black phosphorus)와 같은 반데르 발스 이차원 물질처럼 용도에 따라 반데르 발스 에피택시를 이용하여 원하는 두께나 밴드 갭을 조절하여 이용할 수 있다. 이차원 베타 산화갈륨의 가전자대의 최대점(valence band maximum, VBM)은 도 6d와 같이 XPS를 통해 flat energy distribution과 VB의 leading edge의 선형 피팅(linear fitting)을 통해 계산하였다. 계산된 VBM은 약 4.85 eV로, 2D 베타 산화갈륨의 진성 반도체 n 타입(intrinsic n-type) 특성을 보여준다. 또한 도 6a ~ 6d로부터 계산된 2D 베타 산화갈륨의 VBM-core delta 영역과 에너지 밴드 구조는 도 6e에 요약하였다. Here, α = the absorption coefficient, hυ = the photon energy, c = constant. The optical band gap of 2D beta gallium oxide derived from the Tauc plot as shown in the inset of FIG. 6c is about 5.34 eV, and the band gap of bulk beta gallium oxide (4.7-4.9) eV) has a larger value. Since the thickness of the 2D beta gallium oxide thin film formed by the squeezing method is about 2-3 nm, which is smaller than the exciton Bohr radius of beta gallium oxide, 3.29 nm, the observed band gap difference is strong quantum This can be explained by the effect of the quantum confinement effect. In addition, the band gap of 2D beta gallium oxide enables the formation of an additional beta gallium oxide layer using van der Waals epitaxy, epitaxial growth. After forming the first beta gallium oxide layer through compression and heat treatment as shown in FIG. 3, the same process may be repeated thereon to additionally form a beta gallium oxide layer. After forming an additional 3.2 nm beta gallium oxide layer on the 2 nm thick beta gallium oxide layer, the E g was about 5.18 eV, and a decrease in the optical band gap was observed due to the decrease in the quantum confinement effect. Therefore, like the existing van der Waals two-dimensional materials such as TMD or black phosphorus, the desired thickness or band gap can be adjusted using van der Waals epitaxy according to the application. The valence band maximum (VBM) of the two-dimensional beta gallium oxide was calculated by linear fitting of the leading edge of VB and flat energy distribution through XPS as shown in FIG. 6d. The calculated VBM is about 4.85 eV, showing the intrinsic semiconductor n-type characteristics of 2D beta gallium oxide. Also, the VBM-core delta region and energy band structure of 2D beta gallium oxide calculated from FIGS. 6a to 6d are summarized in FIG. 6e.
2.3 다양한 기판에서의 2차원 베타 산화갈륨 박막 성장2.3 Two-dimensional Beta Gallium Oxide Thin Film Growth on Various Substrates
도 7a는 그래핀(graphene), 쿼츠(quartz), Si(100), 사파이어(sapphire) 기판에서 성장된 베타 산화갈륨 박막의 광학 현미경 이미지(optical microscope image)이고, 도 7b는 베타 산화갈륨 박막의 표면 거칠기(surface topography)를 나타내며, 도 7c는 베타 산화갈륨 박막의 라만 스펙트럼(raman spectra)이고, 도 7d는 베타 산화갈륨 박막의 XRD(x-ray diffraction pattern) 스펙트럼을 나타낸다.7A is an optical microscope image of a beta gallium oxide thin film grown on a graphene, quartz, Si(100), or sapphire substrate, and FIG. 7B is an optical microscope image of a beta gallium oxide thin film. Shows the surface roughness (surface topography), Figure 7c is a Raman spectrum (raman spectra) of the beta gallium oxide thin film, Figure 7d shows the XRD (x-ray diffraction pattern) spectrum of the beta gallium oxide thin film.
모든 기판에서 베타 산화갈륨은 밀리미터 스케일의 void-free full coverage를 보였고, rms는 각각 0.76, 1.5, 2.2, 그리고 14 nm 이었다. 성장된 나노 베타 산화갈륨 박막의 거칠기(roughness)는 두 가지 요소에 의해 영향을 받는다. 첫 번째 요소는 하부 기판의 거칠기이다. 그래핀(Graphene), 쿼츠(quartz), Si, 사파이어(sapphire) 기판의 rms는 각각 0.67, 1.5, 0.86, 9.9 nm 였는데, 이는 베타 산화갈륨 박막의 rms와 유사하다. 하지만 Si 기판의 경우 기판의 낮은 rms에도 불구하고 박막은 높은 거칠기를 갖는데, 이는 계면 장력(interface tension)의 영향으로 설명할 수 있다. 액상 갈륨은 낮은 점도와 높은 표면 에너지(surface energy)를 갖지만 Cabrera-Mott oxidation의 결과로 형성되는 표면 산화(surface oxide)의 영향으로 친수성(hydrophilic) 기판에 대해 높은 젖음성(wettability)를 갖는다. 따라서 Si이나 표면 에너지가 높은 Pt 기판에서도 높은 계면 장력에 의한 비젖음성(dewetting)을 갖는다(도 7b 참조). UV/오존, 산소 플라즈마(oxygen plasma), 산 에칭(acid etching)과 같은 방법으로 표면 에너지를 조절하고, 이를 통해 젖음성을 제어할 수 있다. In all substrates, beta gallium oxide showed millimeter-scale void-free full coverage, and rms were 0.76, 1.5, 2.2, and 14 nm, respectively. The roughness of the grown nano beta gallium oxide thin film is affected by two factors. The first factor is the roughness of the underlying substrate. The rms of the graphene, quartz, Si, and sapphire substrates were 0.67, 1.5, 0.86, and 9.9 nm, respectively, which is similar to the rms of the beta gallium oxide thin film. However, in the case of the Si substrate, the thin film has high roughness despite the low rms of the substrate, which can be explained by the effect of the interface tension. Liquid gallium has low viscosity and high surface energy, but has high wettability to hydrophilic substrates under the influence of surface oxides formed as a result of Cabrera-Mott oxidation. Therefore, even on a Si or Pt substrate with high surface energy, it has dewetting due to high interfacial tension (see FIG. 7b ). The surface energy can be adjusted by methods such as UV/ozone, oxygen plasma, and acid etching, thereby controlling the wettability.
도 7c와 7d는 각각 그래핀(graphene), 쿼츠(quartz), Si, 그리고 사파이어(sapphire) 위에서 성장한 베타 산화갈륨의 라만과 XRD 스펙트럼을 나타낸다. 모든 기판에서 베타 산화갈륨의 특성화 라만 피크와 회절 피크가 관찰되었다. 액상 갈륨의 압착을 이용한 박막의 성장은 기판에 반데르 발스 힘으로 접착된 산화갈륨층의 산화에 의존하기 때문에 하부 기판의 격자 상수(lattice constant)에 영향이 없이 다양한 기판에서 베타 산화갈륨층의 형성을 가능하게 한다. 이는 향후 이형 구조(heteroustructure)를 이용하여 유연기판, 투명기판 등을 포함한 다양한 기능을 가진 기판과의 통합이 가능할 것으로 예상된다. Si과 사파이어 기판에서 알파 산화갈륨의 특징이 일부 관찰되었다. 변형된(strained) 베타 산화갈륨에 충분한 열 에너지가 공급되면 알파 산화갈륨으로의 상 변화가 발생할 수 있는데, 베타 산화갈륨 내부에 걸리는 스트레인(strain)은 내부 에너지(internal energy)를 상승시켜 쌍결정 경계(twin boundary)로부터 육방정계(hexagonal) 형태의 준안정(metastable)한 α 상으로의 상 변화를 통해 스트레인을 완화(relaxation) 시킨다(도 7e 참조). 따라서 기판의 표면 모폴로지(surface morphology)나 표면 에너지 차이에 의해 야기되는 산화갈륨층의 스트레인에 의해 α와 β 상이 섞인 이종상의 산화갈륨(heterophase Ga2O3)이 형성될 수 있다. 이러한 준안정 알파 산화갈륨은 β 상에 비하여 더 넓은 밴드 갭을 갖기 때문에 ultra-high breakdown transistor나 deep UV opto-electronics at sub-240 nm wavelength의 후보 물질로써 관심이 높아지고 있다. 7c and 7d show Raman and XRD spectra of beta gallium oxide grown on graphene, quartz, Si, and sapphire, respectively. Characterization of beta gallium oxide Raman peaks and diffraction peaks were observed on all substrates. Formation of beta gallium oxide layers on various substrates without affecting the lattice constant of the lower substrate because the growth of thin films using liquid gallium compression depends on the oxidation of the gallium oxide layer adhered to the substrate by van der Waals force. makes it possible It is expected that integration with substrates with various functions including flexible substrates and transparent substrates will be possible in the future using a heterostructure. Some characteristics of alpha gallium oxide were observed on Si and sapphire substrates. When sufficient thermal energy is supplied to strained beta gallium oxide, a phase change to alpha gallium oxide may occur. The strain is relaxed through a phase change from the twin boundary to the hexagonal-shaped metastable α phase (refer to FIG. 7e ). Accordingly, a heterophase Ga 2 O 3 in which α and β phases are mixed may be formed by a strain of the gallium oxide layer caused by a difference in surface morphology or surface energy of the substrate. Since this metastable alpha gallium oxide has a wider band gap than that of the β phase, interest is growing as a candidate material for ultra-high breakdown transistors or deep UV opto-electronics at sub-240 nm wavelength.
이상 본 발명을 구체적인 실시예를 통하여 상세히 설명하였으나, 이는 본 발명을 구체적으로 설명하기 위한 것으로, 본 발명은 이에 한정되지 않으며, 본 발명의 기술적 사상 내에서 당 분야의 통상의 지식을 가진 자에 의해 그 변형이나 개량이 가능함이 명백하다.Although the present invention has been described in detail through specific examples, this is for the purpose of describing the present invention in detail, and the present invention is not limited thereto. It is clear that the modification or improvement is possible.
본 발명의 단순한 변형 내지 변경은 모두 본 발명의 영역에 속한 것으로 본 발명의 구체적인 보호 범위는 첨부된 특허청구범위에 의하여 명확해질 것이다.All simple modifications or changes of the present invention are within the scope of the present invention, and the specific scope of protection of the present invention will be made clear by the appended claims.
본 발명은 기판 상에 액적(droplet) 형태의 액상 갈륨을 전사 및 압착하여 2D 산화갈륨층을 생성하고, 그 산화갈륨층에 대한 열처리를 통해 2D 베타 산화갈륨층을 형성함으로써 베타 산화갈륨 박막을 제조하는 기술이므로 산업상 이용가능성이 인정된다.The present invention prepares a beta gallium oxide thin film by transferring and compressing liquid gallium in the form of droplets on a substrate to generate a 2D gallium oxide layer, and forming a 2D beta gallium oxide layer through heat treatment on the gallium oxide layer It is a technology that can be used for industrial purposes.

Claims (8)

  1. (a) 기판 상에, 액적(droplet) 형태로 액상 갈륨을 전사하는 단계;(a) transferring liquid gallium on a substrate in the form of droplets;
    (b) 압착판으로 전사된 상기 액상 갈륨을 압착하여, 2차원 박막 형태의 산화갈륨층을 형성하는 단계; 및(b) compressing the liquid gallium transferred to a compression plate to form a two-dimensional thin film-type gallium oxide layer; and
    (c) 상기 산화갈륨층을 열처리하여, 2차원 박막 형태의 베타 산화갈륨층을 형성하는 단계;를 포함하는 베타 산화갈륨 박막 제조방법.(c) heat-treating the gallium oxide layer to form a beta gallium oxide layer in the form of a two-dimensional thin film; beta gallium oxide thin film manufacturing method comprising a.
  2. 청구항 1에 있어서,The method according to claim 1,
    상기 (a) 단계는,The step (a) is,
    마이크로 피펫(micro pipet)을 이용해, 상기 액상 갈륨을 액적 형태로, 상기 기판 상에 떨어뜨리는 단계;를 포함하는 베타 산화갈륨 박막 제조방법.Using a micro pipet (micro pipet) to drop the liquid gallium in the form of droplets on the substrate; Beta gallium oxide thin film manufacturing method comprising a.
  3. 청구항 1에 있어서,The method according to claim 1,
    상기 (a) 단계는,The step (a) is,
    30℃ 이상으로 가열된 핫 플레이트(hot plate) 상에, 상기 기판을 배치하는 단계; 및placing the substrate on a hot plate heated to 30° C. or higher; and
    상기 기판 상에 상기 액상 갈륨을 떨어뜨리는 단계;를 포함하는 베타 산화갈륨 박막 제조방법.Dropping the liquid gallium on the substrate; Beta gallium oxide thin film manufacturing method comprising a.
  4. 청구항 1에 있어서,The method according to claim 1,
    상기 (b) 단계에서,In step (b),
    0.5 ~ 50 N의 압착력으로 상기 액상 갈륨을 압착하는 베타 산화갈륨 박막 제조방법.A method for producing a beta gallium oxide thin film for compressing the liquid gallium with a compression force of 0.5 to 50 N.
  5. 청구항 1에 있어서,The method according to claim 1,
    상기 (b) 단계에서,In step (b),
    압착한 상기 압착판은, 상기 산화갈륨층의 상부면에 대해 수직한 방향으로 이격되면서 제거되는 베타 산화갈륨 박막 제조방법.The pressed plate is a beta gallium oxide thin film manufacturing method that is removed while being spaced apart in a direction perpendicular to the upper surface of the gallium oxide layer.
  6. 청구항 1에 있어서,The method according to claim 1,
    상기 (c) 단계에서,In step (c),
    500 ~ 1000℃의 온도로 열처리하는 베타 산화갈륨 박막 제조방법.A method for producing a beta gallium oxide thin film that is heat treated at a temperature of 500 ~ 1000℃.
  7. 청구항 1에 있어서,The method according to claim 1,
    상기 (a) 단계에서 전사되는 상기 액상 갈륨의 양, 및 상기 (b) 단계에서 상기 액상 갈륨을 압착하는 압착력에 의해, 상기 베타 산화갈륨 박막의 두께 및 면적이 조절되는 베타 산화갈륨 박막 제조방법.A method for manufacturing a beta gallium oxide thin film in which the thickness and area of the beta gallium oxide thin film are controlled by the amount of the liquid gallium transferred in step (a), and the compressive force for compressing the liquid gallium in step (b).
  8. 청구항 1에 있어서,The method according to claim 1,
    상기 (c) 단계 이후에,After step (c),
    상기 (c) 단계에서 생성된 상기 베타 산화갈륨층 상에, 상기 (a) 단계에 따른 액상 전사 단계, 상기 (b) 단계에 따른 산화갈륨층 형성 단계, 및 상기 (c) 단계에 따른 베타 산화갈륨층 형성 단계를 순차적으로, n(n≥1, 자연수) 회 추가 수행하여, 상기 기판 상에 n+1(n≥1, 자연수) 개의 상기 베타 산화갈륨층을 적층시키는 베타 산화갈륨 박막 제조방법.On the beta gallium oxide layer generated in step (c), the liquid phase transfer step according to step (a), the gallium oxide layer formation step according to step (b), and beta oxidation according to step (c) A method for manufacturing a beta gallium oxide thin film in which the gallium layer forming step is sequentially performed n (n≥1, natural number) times additionally to stack n+1 (n≥1, natural number) beta gallium oxide layers on the substrate .
PCT/KR2021/006391 2020-06-05 2021-05-24 METHOD FOR FABRICATING β-GA2O3 THIN FILM WO2021246697A1 (en)

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CN115558980A (en) * 2022-10-14 2023-01-03 中山大学 Method for preparing gallium oxide film by heating and spin coating synchronous combined annealing process

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