CN109638136B - Transparent electrode of light-emitting diode and preparation method thereof - Google Patents
Transparent electrode of light-emitting diode and preparation method thereof Download PDFInfo
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- 238000002360 preparation method Methods 0.000 title claims abstract description 20
- 229910052738 indium Inorganic materials 0.000 claims abstract description 87
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 claims abstract description 87
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 68
- 239000001301 oxygen Substances 0.000 claims abstract description 68
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 68
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims abstract description 63
- 238000006243 chemical reaction Methods 0.000 claims abstract description 45
- 238000000034 method Methods 0.000 claims abstract description 31
- 238000004140 cleaning Methods 0.000 claims abstract description 21
- 230000001681 protective effect Effects 0.000 claims abstract description 21
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 claims abstract description 10
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 claims abstract 4
- 229910002601 GaN Inorganic materials 0.000 claims description 47
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 claims description 43
- 230000001276 controlling effect Effects 0.000 claims description 15
- 238000007781 pre-processing Methods 0.000 claims description 13
- 230000001105 regulatory effect Effects 0.000 claims description 13
- 239000000463 material Substances 0.000 claims description 10
- IBEFSUTVZWZJEL-UHFFFAOYSA-N trimethylindium Chemical group C[In](C)C IBEFSUTVZWZJEL-UHFFFAOYSA-N 0.000 claims description 9
- 239000010409 thin film Substances 0.000 claims description 8
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 claims description 6
- WHXTVQNIFGXMSB-UHFFFAOYSA-N n-methyl-n-[tris(dimethylamino)stannyl]methanamine Chemical compound CN(C)[Sn](N(C)C)(N(C)C)N(C)C WHXTVQNIFGXMSB-UHFFFAOYSA-N 0.000 claims description 5
- CRHIAMBJMSSNNM-UHFFFAOYSA-N tetraphenylstannane Chemical compound C1=CC=CC=C1[Sn](C=1C=CC=CC=1)(C=1C=CC=CC=1)C1=CC=CC=C1 CRHIAMBJMSSNNM-UHFFFAOYSA-N 0.000 claims description 4
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 claims description 3
- 235000013842 nitrous oxide Nutrition 0.000 claims description 3
- RWWNQEOPUOCKGR-UHFFFAOYSA-N tetraethyltin Chemical compound CC[Sn](CC)(CC)CC RWWNQEOPUOCKGR-UHFFFAOYSA-N 0.000 claims description 3
- VXKWYPOMXBVZSJ-UHFFFAOYSA-N tetramethyltin Chemical compound C[Sn](C)(C)C VXKWYPOMXBVZSJ-UHFFFAOYSA-N 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 229910001868 water Inorganic materials 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 2
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- 229910052751 metal Inorganic materials 0.000 description 14
- 239000002184 metal Substances 0.000 description 14
- 238000007788 roughening Methods 0.000 description 9
- 229910052786 argon Inorganic materials 0.000 description 7
- 239000012159 carrier gas Substances 0.000 description 7
- 239000013078 crystal Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 239000004065 semiconductor Substances 0.000 description 5
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- 238000001755 magnetron sputter deposition Methods 0.000 description 3
- 238000001000 micrograph Methods 0.000 description 3
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- 238000002834 transmittance Methods 0.000 description 3
- 238000001039 wet etching Methods 0.000 description 3
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
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- 229910001020 Au alloy Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- 239000010931 gold Substances 0.000 description 1
- 239000003353 gold alloy Substances 0.000 description 1
- MSNOMDLPLDYDME-UHFFFAOYSA-N gold nickel Chemical compound [Ni].[Au] MSNOMDLPLDYDME-UHFFFAOYSA-N 0.000 description 1
- 230000009643 growth defect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910003437 indium oxide Inorganic materials 0.000 description 1
- PJXISJQVUVHSOJ-UHFFFAOYSA-N indium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[In+3].[In+3] PJXISJQVUVHSOJ-UHFFFAOYSA-N 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000001451 molecular beam epitaxy Methods 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 239000004038 photonic crystal Substances 0.000 description 1
- 229920002120 photoresistant polymer Polymers 0.000 description 1
- 238000004549 pulsed laser deposition Methods 0.000 description 1
- 238000003892 spreading Methods 0.000 description 1
- 230000007480 spreading Effects 0.000 description 1
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- 239000011787 zinc oxide Substances 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/36—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
- H01L33/40—Materials therefor
- H01L33/42—Transparent materials
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
- H01L2933/0008—Processes
- H01L2933/0016—Processes relating to electrodes
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- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Led Devices (AREA)
- Chemical Vapour Deposition (AREA)
- Electrodes Of Semiconductors (AREA)
Abstract
The invention provides a transparent electrode of a light-emitting diode, and a preparation method comprises the following steps: s1, chemically cleaning the surface of an epitaxial wafer, then placing the epitaxial wafer into an MOCVD reaction chamber, keeping the temperature at 900 ℃ and the pressure at 3-100Torr, and processing for 1-60 min; s2, under the protective atmosphere, adjusting the growth temperature to be 450-650 ℃, adjusting the pressure of the reaction cavity to be 3-80Torr, then introducing an indium source, a tin source and an oxygen source, controlling the growth speed to be 0.1-3nm/min, and growing an ITO (indium tin oxide) main body layer with the thickness of 40-500nm on the surface of the pretreated epitaxial wafer; s3, under the protective atmosphere, adjusting the growth temperature to be 300-450 ℃, adjusting the pressure of the reaction cavity to be 3-80Torr, then introducing an indium source, a tin source and an oxygen source, controlling the growth speed to be 1-10nm/min, and growing an ITO coarsening layer with the thickness of 20-200nm on the ITO main body layer. The method for growing the coarsening layer in situ is very suitable for the preparation method of the ITO transparent electrode main body layer, avoids subsequent complex process treatment, and can effectively improve the light extraction efficiency of the LED.
Description
Technical Field
The invention belongs to the technical field of semiconductor materials and semiconductor photoelectric devices, and mainly relates to an ITO transparent electrode for a gallium nitride-based LED and a preparation method thereof.
Background
In the practical application of a nitride-based Light Emitting Diode (LED), because the P-type layer of the LED has high resistivity and a large work function, a transparent conductive thin film material such as nickel-gold alloy (Ni/Au), zinc oxide doped Aluminum (AZO), or indium oxide doped tin (ITO) is often used as a transparent electrode to achieve a current spreading effect and a low specific contact resistance. The transparent electrode thin film material used in the above method has a high visible light (400-.
Among many transparent conductive materials, the ITO film is the most widely used transparent conductive material with the mature process at present due to its advantages of high light transmittance, good conductivity, good thermal stability, strong substrate adhesion, etc. Currently, ITO thin films are mainly grown by means of magnetron sputtering, molecular beam epitaxy, pulsed laser deposition, and Metal Organic Chemical Vapor Deposition (MOCVD). Among them, the magnetron sputtering method has been widely applied to the blue-light LED industry, while the MOCVD method has less application to the preparation of ITO thin films. But the MOCVD method for preparing the ITO film has the advantages of uniformity, accurate and controllable doping amount, suitability for large-area production and the like. According to the literature, the ITO film prepared by the MOCVD method not only has the conductivity similar to that of the magnetron sputtering method, but also has higher transmittance in the near ultraviolet wave band of 365nm (the literature: Zhuoetal, "Structural, electrochemical properties of indium tin oxide film growth by metallic organic chemical vapor deposition with a tetramethylmulti-layer", Japanese journal of applied physics, 2018; 57(1): 5.).
Further, in patent application CN106968015A, an ultraviolet transparent conductive film and a manufacturing method thereof are introduced, which illustrate that an ITO transparent conductive film with high transmittance in both ultraviolet and visible bands can be prepared by an MOCVD method, and the application range of the ITO transparent conductive film material is expanded to a deep ultraviolet band of 300 nm. Chen et al applied an ITO film prepared by MOCVD method to an ultraviolet LED as a transparent electrode and achieved excellent properties (document: Chen Z, et al, "high ultra violet transparent treated indium tin oxide films and applied coatings in light emitting diodes", applied Phys Lett.2017; 110(24): 242101.). These all show that the ITO transparent electrode prepared by the MOCVD method has great potential for being applied to gallium nitride-based light-emitting diodes with light-emitting wavelength from ultraviolet to visible.
In order to further improve the photoelectric conversion efficiency of an LED using MOCVD-ITO, it is necessary to improve the light extraction efficiency. Considering the epitaxial relationship between gallium nitride-based materials and ITO materials, in general, the ITO thin film grown on the LED by MOCVD has a preferred (111) orientation, and since the (111) crystal plane is the most thermodynamically stable crystal plane, the ITO thin film on the LED tends to form a flat surface. Therefore, surface roughening is a simple and effective method for improving light extraction efficiency. Patent CN106025027B discloses roughening a selective region of an N-type semiconductor layer to form a roughened region and a non-roughened current blocking region, thereby obtaining an N-type semiconductor roughened layer, wherein the roughened region is roughened by using an N-type semiconductor roughening solution to form a plurality of individual taper bumps, and the P-type layer leaks between the taper bumps. Patent CN101248537B discloses a light emitting diode comprising a roughened layer of transparent material, the roughening method being a combination of photolithography for creating a pattern and dry or wet photo-electrochemical (PEC) etching for creating a texture. Patent application CN105206713A discloses a method for improving GaN-LED luminous efficiency, after ITO patterning holes, a photoresist mask is reserved, an ICP method is adopted to etch p-GaN, InGaN multiple quantum wells and part of n-GaN in a hollow area, and absorption of the non-luminous area to light is reduced; meanwhile, by controlling the appearance of the mask and ICP conditions, bowl-shaped, truncated cone-shaped or cylindrical pits are etched in the hollow area, so that the purposes of surface roughening and LED light emitting improvement are achieved.
It can be seen that the existing surface roughening methods generally include dry etching and wet etching or photonic crystal-based techniques, and the roughening methods can improve the light extraction efficiency, but the overall process is complex and the cost is high.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides the ITO transparent electrode for the gallium nitride-based LED, the ITO transparent electrode is prepared by adopting an MOCVD method, and the surface roughening is realized through in-situ growth on the premise of not introducing subsequent process treatment. The preparation process is extremely simple, easy to control, low in cost and convenient for industrial production.
In order to achieve the purpose, the invention adopts the following technical scheme:
a transparent electrode of a light emitting diode, the transparent electrode comprising an ITO body layer grown on a gallium nitride-based LED and an ITO coarsening layer grown on the ITO body layer;
the preparation method of the transparent electrode of the light-emitting diode comprises the following steps:
s1, preprocessing a gallium nitride-based LED epitaxial wafer: chemically cleaning the surface of the epitaxial wafer, then placing the epitaxial wafer into an MOCVD reaction chamber, keeping the temperature at 300 ℃ and 900 ℃ and the pressure at 3-100Torr, and treating for 1-60 min;
s2, growing an ITO main body layer: under the protective atmosphere, regulating the growth temperature to be 450-650 ℃, regulating the pressure of the reaction cavity to be 3-80Torr, then introducing an indium source, a tin source and an oxygen source, growing an ITO (indium tin oxide) main body layer with the thickness of 40-500nm on the surface of the pretreated epitaxial wafer, and controlling the growth speed to be 0.1-3 nm/min;
s3, growing an ITO coarsening layer: under the protective atmosphere, the growth temperature is adjusted to be 300-450 ℃, the pressure of the reaction cavity is adjusted to be 3-80Torr, then an indium source, a tin source and an oxygen source are introduced, an ITO coarsening layer with the thickness of 20-200nm is grown on the ITO main body layer, and the growth speed is controlled to be 1-10 nm/min;
the molar flow ratio of the indium source to the tin source in S2 and S3 is 4:1-100:1, and the molar flow ratio of the indium source to the oxygen source in S2 and S3 is 1:100-1: 10000.
The ITO transparent electrode has the advantages that the main body layer of the ITO transparent electrode has lower resistivity, good current expansion can be realized, the ITO transparent electrode has lower specific contact resistance when being contacted with a p-type material of a gallium nitride-based LED epitaxial wafer, and the ITO transparent electrode has extremely low absorptivity in ultraviolet to visible light wave bands; the invention innovatively introduces a coarsening layer through researching the growth mechanism of the ITO film, and realizes the conversion of the exposed crystal face of the film by changing the growth condition of the MOCVD film, thereby changing the surface appearance of the film and realizing the coarsening effect. The method for growing the coarsening layer in situ is very suitable for the preparation method of the ITO transparent electrode main body layer, avoids subsequent complex process treatment, and can effectively improve the light extraction efficiency of the LED.
The ITO transparent electrode comprises an ITO main body layer and an ITO coarsening layer which are sequentially grown on the gallium nitride-based LED. The ITO main body layer plays a role of a main transparent electrode, and current expansion and good ohmic contact with a P-type layer of the LED are achieved. The ITO coarsening layer plays a coarsening role.
Preferably, the preparation method of the transparent electrode of the light emitting diode comprises the following steps:
s1, preprocessing a gallium nitride-based LED epitaxial wafer: chemically cleaning the surface of the epitaxial wafer, then placing the epitaxial wafer into an MOCVD reaction chamber, keeping the temperature at 600 ℃ and the pressure at 20Torr, and processing for 20 min;
s2, growing an ITO main body layer: under the protective atmosphere, adjusting the growth temperature to 530 ℃ and 600 ℃, adjusting the pressure of the reaction cavity to 6-15Torr, then introducing an indium source, a tin source and an oxygen source, adjusting the molar flow ratio of the flow control indium source to the tin source to be 5:1-50:1, adjusting the molar flow ratio of the flow control indium source to the oxygen source to be 1:500-1:3000, growing an ITO (indium tin oxide) main body layer with the thickness of 80-150nm on the surface of the pretreated epitaxial wafer, and controlling the growth speed to be 1-2 nm/min;
s3, growing an ITO coarsening layer: under the protective atmosphere, the growth temperature is adjusted to 430 ℃, the pressure of the reaction cavity is adjusted to 9Torr, then an indium source, a tin source and an oxygen source are introduced, the molar flow ratio of the indium source to the tin source is adjusted and controlled to be 5:1-50:1, the molar flow ratio of the indium source to the oxygen source is adjusted and controlled to be 1:1000-1:4000, an ITO rough layer with the thickness of 50-100nm is grown on the ITO main body layer, and the growth speed is controlled to be 2-5 nm/min.
Preferably, the preparation method of the transparent electrode of the light emitting diode comprises the following steps:
s1, preprocessing a gallium nitride-based LED epitaxial wafer: chemically cleaning the surface of the epitaxial wafer, then placing the epitaxial wafer into an MOCVD reaction chamber, keeping the temperature at 700 ℃ and the pressure at 10Torr, and processing for 30 min;
s2, growing an ITO main body layer: under the protective atmosphere, adjusting the growth temperature to 530 ℃ and 600 ℃, adjusting the pressure of the reaction cavity to 6-15Torr, then introducing an indium source, a tin source and an oxygen source, adjusting the molar flow ratio of the flow control indium source to the tin source to be 5:1-50:1, adjusting the molar flow ratio of the flow control indium source to the oxygen source to be 1:500-1:3000, growing an ITO (indium tin oxide) main body layer with the thickness of 80-150nm on the surface of the pretreated epitaxial wafer, and controlling the growth speed to be 1-2 nm/min;
s3, growing an ITO coarsening layer: under the protective atmosphere, the growth temperature is adjusted to 380 ℃, the pressure of the reaction cavity is adjusted to 15Torr, then an indium source, a tin source and an oxygen source are introduced, the molar flow ratio of the indium source to the tin source is adjusted and controlled to be 5:1-50:1, the molar flow ratio of the indium source to the oxygen source is adjusted and controlled to be 1:1000-1:4000, an ITO rough layer with the thickness of 50-100nm is grown on the ITO main body layer, and the growth speed is controlled to be 2-5 nm/min.
Preferably, the chemical cleaning of S1 includes organic cleaning and inorganic acid-base cleaning. By the cleaning means, dirty spots on the surface of the epitaxial wafer caused by growth defects can be effectively removed.
Preferably, the surface of the epitaxial wafer of S2 refers to the surface of a P-type layer of the gallium nitride-based LED.
Preferably, the indium source of S2 and S3 is trimethyl indium, and the oxygen source is one of oxygen, laughing gas, water and ozone.
Preferably, the tin source of S2 or S3 is one of tetraethyltin, tetrakis (dimethylamino) tin, tetraphenyltin and tetramethyltin.
Preferably, the crystal plane exposed on the surface of the ITO roughened layer includes, but is not limited to, a (100) crystal plane.
Preferably, the light-emitting wavelength range of the gallium nitride-based LED is 300-760 nm.
Preferably, the ITO transparent electrode is a polycrystalline thin film material with (111) preferred orientation.
Preferably, the molar flow ratio of the indium source to the tin source in S2 and S3 is 5:1 to 50:1, and the molar flow ratio of the indium source to the oxygen source in S2 and S3 is 1:1000 to 1: 3000.
The invention has the beneficial effects that:
the ITO transparent electrode has the advantages that the main body layer of the ITO transparent electrode has lower resistivity, good current expansion can be realized, the ITO transparent electrode has lower specific contact resistance when being contacted with a p-type material of a gallium nitride-based LED epitaxial wafer, and the ITO transparent electrode has extremely low absorptivity in ultraviolet to visible light wave bands; the invention innovatively introduces a coarsening layer through researching the growth mechanism of the ITO film, and realizes the conversion of the exposed crystal face of the film by changing the growth condition of the MOCVD film, thereby changing the surface appearance of the film and realizing the coarsening effect. The method for growing the coarsening layer in situ is very suitable for the preparation method of the ITO transparent electrode main body layer, avoids subsequent complex process treatment, and can effectively improve the light extraction efficiency of the LED.
Drawings
Fig. 1 is a schematic diagram of a full structure of a gallium nitride-based LED according to a technical solution of the present invention.
FIG. 2 is a scanning electron micrograph of an ITO transparent electrode in example 1 of the present invention.
FIG. 3 is a scanning electron micrograph of an ITO transparent electrode in comparative example 1 of the present invention.
FIG. 4 is a scanning electron micrograph of an ITO transparent electrode in example 2 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of the present invention is not limited to the embodiments.
Example 1:
by utilizing the existing MOCVD equipment, organic metal trimethyl indium is used as an indium source, organic metal tetra (dimethylamino) tin is used as a tin source, oxygen with the purity of 99.9999 percent is used as an oxygen source, argon is used as carrier gas and growth protective atmosphere, and an ITO transparent electrode is prepared on a gallium nitride-based ultraviolet 365nm LED.
The preparation method of the ITO transparent electrode of the embodiment is as follows:
s1, preprocessing a gallium nitride-based LED epitaxial wafer: organic and inorganic acid-base cleaning is carried out on the surface of the gallium nitride-based ultraviolet 365nm LED, and then the gallium nitride-based ultraviolet 365nm LED is prevented from contacting air and is placed into an MOCVD reaction cavity as soon as possible. Then, the temperature was controlled at 600 ℃ and the pressure was controlled at 20Torr, and the treatment was carried out for 20 min.
S2, growing an ITO main body layer: the growth temperature is controlled at 530 ℃, the pressure of a reaction cavity is controlled at 9Torr, an indium source, an oxygen source and a tin source are simultaneously introduced, the flow is regulated to control the molar flow ratio of the indium source to the oxygen source to be 1:500, and the molar flow ratio of the indium source to the tin source is 10: 1, controlling the growth speed to be 1.5nm/min, and growing an ITO main body layer with the thickness of 150 nm.
S3, growing an ITO coarsening layer: the growth temperature is controlled at 430 ℃, the pressure of a reaction cavity is controlled at 9Torr, an indium source, an oxygen source and a tin source are simultaneously introduced, the flow is regulated to control the molar flow ratio of the indium source to the oxygen source to be 1:3000, and the molar flow ratio of the indium source to the tin source is 10: 1, controlling the growth speed to be 2.5nm/min, and growing an ITO coarsening layer with the thickness of 80 nm.
Fig. 2 is a scanning electron microscope image of the ITO transparent electrode in this embodiment, and it can be seen that the film prepared in this embodiment has a rough surface morphology, which can effectively improve the light extraction efficiency.
Example 2:
by utilizing the existing MOCVD equipment, organic metal trimethyl indium is used as an indium source, organic tetramethyl tin is used as a tin source, oxygen with the purity of 99.9999 percent is used as an oxygen source, argon is used as carrier gas and growth protective atmosphere, and an ITO transparent electrode is prepared on a gallium nitride-based ultraviolet 460 nmLED.
The preparation method of the ITO transparent electrode of the embodiment is as follows:
s1, preprocessing a gallium nitride-based LED epitaxial wafer: after organic and inorganic acid-base cleaning is carried out on the surface of the gallium nitride-based ultraviolet 460nmLED, the surface is prevented from contacting air and is put into an MOCVD reaction cavity as soon as possible. Then, the temperature was controlled at 700 ℃ and the pressure was controlled at 10Torr, and the treatment was carried out for 30 min.
S2, growing an ITO main body layer: the growth temperature is controlled at 600 ℃, the pressure of a reaction cavity is controlled at 6Torr, an indium source, an oxygen source and a tin source are simultaneously introduced, the flow is regulated to control the molar flow ratio of the indium source to the oxygen source to be 1:1000, and the molar flow ratio of the indium source to the tin source is 20: 1, controlling the growth speed to be 1nm/min, and growing an ITO main body layer with the thickness of 100 nm.
S3, growing an ITO coarsening layer: the growth temperature is controlled at 380 ℃, the pressure of a reaction cavity is controlled at 15Torr, an indium source, an oxygen source and a tin source are introduced simultaneously, the flow is controlled by adjusting the molar flow ratio of the indium source to the oxygen source to be 1:1000, and the molar flow ratio of the indium source to the tin source is 20: 1, controlling the growth speed to be 4nm/min, and growing an ITO coarsening layer with the thickness of 50 nm.
FIG. 4 is a scanning electron microscope image of the ITO transparent electrode in this example, which shows that the ITO transparent electrode has a rough surface morphology.
Example 3:
by utilizing the existing MOCVD equipment, organic metal trimethyl indium is used as an indium source, organic metal tetraethyl tin is used as a tin source, laughing gas is used as an oxygen source, argon is used as carrier gas and growth protective atmosphere, and an ITO transparent electrode is prepared on a gallium nitride-based ultraviolet 300 nmLED.
The preparation method of the ITO transparent electrode of the embodiment is as follows:
s1, preprocessing a gallium nitride-based LED epitaxial wafer: after organic and inorganic acid-base cleaning is carried out on the surface of the gallium nitride-based ultraviolet 300nm LED, the LED is prevented from contacting air and is placed into an MOCVD reaction cavity as soon as possible. Then, the temperature was controlled at 300 ℃ and the pressure was controlled at 100Torr, and the treatment was carried out for 1 min.
S2, growing an ITO main body layer: the growth temperature is controlled at 450 ℃, the pressure of a reaction cavity is controlled at 80Torr, an indium source, an oxygen source and a tin source are simultaneously introduced, the flow is regulated to control the molar flow ratio of the indium source to the oxygen source to be 1:100, the molar flow ratio of the indium source to the tin source to be 4:1, the growth speed is controlled to be 0.1nm/min, and an ITO main body layer with the thickness of 40nm is grown.
S3, growing an ITO coarsening layer: the growth temperature is controlled at 300 ℃, the pressure of a reaction cavity is controlled at 80Torr, an indium source, an oxygen source and a tin source are simultaneously introduced, the flow is regulated to control the molar flow ratio of the indium source to the oxygen source to be 1:100, the molar flow ratio of the indium source to the tin source to be 4:1, the growth speed is controlled to be 1nm/min, and an ITO coarsening layer with the thickness of 20nm is grown.
Example 4:
by utilizing the existing MOCVD equipment, organic metal trimethyl indium is used as an indium source, organic metal tetraphenyl tin is used as a tin source, water is used as an oxygen source, argon is used as carrier gas and growth protective atmosphere, and an ITO transparent electrode is prepared on a gallium nitride-based ultraviolet 760 nmLED.
The preparation method of the ITO transparent electrode of the embodiment is as follows:
s1, preprocessing a gallium nitride-based LED epitaxial wafer: after organic and inorganic acid-base cleaning is carried out on the surface of the gallium nitride-based ultraviolet 760nm LED, the LED is prevented from contacting air and is placed into an MOCVD reaction cavity as soon as possible. Then, the temperature was controlled at 900 ℃ and the pressure was controlled at 3Torr, and the treatment was carried out for 60 min.
S2, growing an ITO main body layer: the growth temperature is controlled at 650 ℃, the pressure of a reaction cavity is controlled at 3Torr, an indium source, an oxygen source and a tin source are simultaneously introduced, the flow is regulated to control the molar flow ratio of the indium source and the oxygen source to be 1:10000, the molar flow ratio of the indium source to the tin source is 100:1, the growth speed is controlled to be 3nm/min, and an ITO main body layer with the thickness of 500nm is grown.
S3, growing an ITO coarsening layer: the growth temperature is controlled at 450 ℃, the pressure of a reaction cavity is controlled at 3Torr, an indium source, an oxygen source and a tin source are introduced simultaneously, the flow is regulated to control the molar flow ratio of the indium source to the oxygen source to be 1:10000, the molar flow ratio of the indium source to the tin source is 100:1, the growth speed is controlled to be 10nm/min, and an ITO coarsening layer with the thickness of 200nm is grown.
Example 5:
by utilizing the existing MOCVD equipment, organic metal trimethyl indium is used as an indium source, organic metal tetraphenyl tin is used as a tin source, ozone is used as an oxygen source, argon is used as carrier gas and growth protective atmosphere, and an ITO transparent electrode is prepared on a gallium nitride-based ultraviolet 500 nmLED.
The preparation method of the ITO transparent electrode of the embodiment is as follows:
s1, preprocessing a gallium nitride-based LED epitaxial wafer: after organic and inorganic acid-base cleaning is carried out on the surface of the gallium nitride-based ultraviolet 500nm LED, the gallium nitride-based ultraviolet 500nm LED is prevented from contacting air and is put into an MOCVD reaction cavity as soon as possible. Then, the temperature was controlled at 700 ℃ and the pressure was controlled at 50Torr, and the treatment was conducted for 10 min.
S2, growing an ITO main body layer: the growth temperature is controlled at 500 ℃, the pressure of a reaction cavity is controlled at 20Torr, an indium source, an oxygen source and a tin source are simultaneously introduced, the flow is regulated to control the molar flow ratio of the indium source to the oxygen source to be 1:4500, the molar flow ratio of the indium source to the tin source to be 25:1, the growth speed is controlled to be 2nm/min, and an ITO main body layer with the thickness of 200nm is grown.
S3, growing an ITO coarsening layer: the growth temperature is controlled at 400 ℃, the pressure of a reaction cavity is controlled at 30Torr, an indium source, an oxygen source and a tin source are introduced simultaneously, the flow is regulated to control the molar flow ratio of the indium source to the oxygen source to be 1:400, the molar flow ratio of the indium source to the tin source is 15:1, the growth speed is controlled to be 5nm/min, and an ITO coarsening layer with the thickness of 150nm is grown.
Example 6:
by utilizing the existing MOCVD equipment, organic metal trimethyl indium is used as an indium source, organic metal tetra (dimethylamino) tin is used as a tin source, oxygen with the purity of 99.9999 percent is used as an oxygen source, argon is used as carrier gas and growth protective atmosphere, and an ITO transparent electrode is prepared on a gallium nitride-based ultraviolet 365nm LED.
The preparation method of the ITO transparent electrode of the embodiment is as follows:
s1, preprocessing a gallium nitride-based LED epitaxial wafer: organic and inorganic acid-base cleaning is carried out on the surface of the gallium nitride-based ultraviolet 365nm LED, and then the gallium nitride-based ultraviolet 365nm LED is prevented from contacting air and is placed into an MOCVD reaction cavity as soon as possible. Then, the temperature was controlled at 600 ℃ and the pressure was controlled at 20Torr, and the treatment was carried out for 20 min.
S2, growing an ITO main body layer: the growth temperature is controlled at 530 ℃, the pressure of a reaction cavity is controlled at 15Torr, an indium source, an oxygen source and a tin source are introduced simultaneously, the flow is controlled by adjusting the molar flow ratio of the indium source to the oxygen source to be 1:3000, and the molar flow ratio of the indium source to the tin source is 5:1, controlling the growth speed to be 2nm/min, and growing an ITO main body layer with the thickness of 80 nm.
S3, growing an ITO coarsening layer: the growth temperature is controlled at 430 ℃, the pressure of a reaction cavity is controlled at 9Torr, an indium source, an oxygen source and a tin source are simultaneously introduced, the flow is controlled by adjusting the molar flow ratio of the indium source to the oxygen source to be 1:4000, and the molar flow ratio of the indium source to the tin source is 5:1, controlling the growth speed to be 2nm/min, and growing an ITO coarsening layer with the thickness of 100 nm.
Example 7:
by utilizing the existing MOCVD equipment, organic metal trimethyl indium is used as an indium source, organic metal tetra (dimethylamino) tin is used as a tin source, oxygen with the purity of 99.9999 percent is used as an oxygen source, argon is used as carrier gas and growth protective atmosphere, and an ITO transparent electrode is prepared on a gallium nitride-based ultraviolet 365nm LED.
The preparation method of the ITO transparent electrode of the embodiment is as follows:
s1, preprocessing a gallium nitride-based LED epitaxial wafer: organic and inorganic acid-base cleaning is carried out on the surface of the gallium nitride-based ultraviolet 365nm LED, and then the gallium nitride-based ultraviolet 365nm LED is prevented from contacting air and is placed into an MOCVD reaction cavity as soon as possible. Then, the temperature was controlled at 700 ℃ and the pressure was controlled at 10Torr, and the treatment was carried out for 30 min.
S2, growing an ITO main body layer: the growth temperature is controlled at 530 ℃, the pressure of a reaction cavity is controlled at 15Torr, an indium source, an oxygen source and a tin source are introduced simultaneously, the flow is controlled by adjusting the molar flow ratio of the indium source to the oxygen source to be 1:3000, and the molar flow ratio of the indium source to the tin source is 50:1, controlling the growth speed to be 2nm/min, and growing an ITO main body layer with the thickness of 80 nm.
S3, growing an ITO coarsening layer: the growth temperature is controlled at 380 ℃, the pressure of a reaction cavity is controlled at 15Torr, an indium source, an oxygen source and a tin source are introduced simultaneously, the flow is controlled by adjusting the molar flow ratio of the indium source to the oxygen source to be 1:4000, and the molar flow ratio of the indium source to the tin source is 50:1, controlling the growth speed to be 5nm/min, and growing an ITO coarsening layer with the thickness of 100 nm.
Comparative example 1:
compared with the example 1, the growth of the ITO coarsening layer of the step 3 is not carried out, and other operation steps are the same as the example 1.
FIG. 3 is a scanning electron microscope image of the ITO transparent electrode of this comparative example. As can be seen, the surface topography of the sample without the addition of the roughening layer in this comparative example is relatively flat.
Comparative example 2:
compared with the embodiment 1, the ITO coarse layer is prepared by wet etching to replace the growth of the ITO coarse layer in the step 3, and other operation steps are the same as the embodiment 1.
Compared with the embodiment 1, the wet etching process method needs additional process steps and corresponding equipment, and is high in cost and complex in operation.
Variations and modifications to the above-described embodiments may occur to those skilled in the art, which fall within the scope and spirit of the above description. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and variations of the present invention should fall within the scope of the claims of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
Claims (4)
1. A transparent electrode of a light-emitting diode is characterized in that the transparent electrode is an ITO (indium tin oxide) main body layer grown on a gallium nitride-based LED (light-emitting diode) and an ITO coarsening layer grown on the ITO main body layer;
the preparation method of the transparent electrode of the light-emitting diode comprises the following steps:
s1, preprocessing a gallium nitride-based LED epitaxial wafer: chemically cleaning the surface of the epitaxial wafer, then placing the epitaxial wafer into an MOCVD reaction chamber, keeping the temperature at 300 ℃ and 900 ℃ and the pressure at 3-100Torr, and treating for 1-60 min;
s2, growing an ITO main body layer: under the protective atmosphere, regulating the growth temperature to be 450-650 ℃, regulating the pressure of the reaction cavity to be 3-80Torr, then introducing an indium source, a tin source and an oxygen source, growing an ITO (indium tin oxide) main body layer with the thickness of 40-500nm on the surface of the pretreated epitaxial wafer, and controlling the growth speed to be 0.1-3 nm/min;
s3, growing an ITO coarsening layer: under the protective atmosphere, the growth temperature is adjusted to be 300-450 ℃, the pressure of the reaction cavity is adjusted to be 3-80Torr, then an indium source, a tin source and an oxygen source are introduced, an ITO coarsening layer with the thickness of 20-200nm is grown on the ITO main body layer, and the growth speed is controlled to be 1-10 nm/min;
the molar flow ratio of the indium source to the tin source in S2 and S3 is 5:1-50:1, and the molar flow ratio of the indium source to the oxygen source in S2 and S3 is 1:1000-1: 3000;
the ITO transparent electrode is a polycrystalline thin film material with (111) preferred orientation,
s1 the chemical cleaning comprises organic cleaning and inorganic acid-base cleaning,
s2 the surface of the epitaxial wafer refers to the surface of a P-type layer of the GaN-based LED,
s2 and S3, the indium source is trimethyl indium, the oxygen source is one of oxygen, laughing gas, water and ozone, and the tin source is one of tetraethyltin, tetra (dimethylamino) tin, tetraphenyltin and tetramethyltin in S2 and S3.
2. The transparent electrode of the light-emitting diode according to claim 1, wherein the method for preparing the transparent electrode of the light-emitting diode comprises the following steps:
s1, preprocessing a gallium nitride-based LED epitaxial wafer: chemically cleaning the surface of the epitaxial wafer, then placing the epitaxial wafer into an MOCVD reaction chamber, keeping the temperature at 600 ℃ and the pressure at 20Torr, and processing for 20 min;
s2, growing an ITO main body layer: under the protective atmosphere, adjusting the growth temperature to 530 ℃ and 600 ℃, adjusting the pressure of the reaction cavity to 6-15Torr, then introducing an indium source, a tin source and an oxygen source, adjusting the molar flow ratio of the flow control indium source to the tin source to be 5:1-50:1, adjusting the molar flow ratio of the flow control indium source to the oxygen source to be 1:500-1:3000, growing an ITO (indium tin oxide) main body layer with the thickness of 80-150nm on the surface of the pretreated epitaxial wafer, and controlling the growth speed to be 1-2 nm/min;
s3, growing an ITO coarsening layer: under the protective atmosphere, the growth temperature is adjusted to 430 ℃, the pressure of the reaction cavity is adjusted to 9Torr, then an indium source, a tin source and an oxygen source are introduced, the molar flow ratio of the indium source to the tin source is adjusted and controlled to be 5:1-50:1, the molar flow ratio of the indium source to the oxygen source is adjusted and controlled to be 1:1000-1:4000, an ITO rough layer with the thickness of 50-100nm is grown on the ITO main body layer, and the growth speed is controlled to be 2-5 nm/min.
3. The transparent electrode of the light-emitting diode according to claim 1, wherein the method for preparing the transparent electrode of the light-emitting diode comprises the following steps:
s1, preprocessing a gallium nitride-based LED epitaxial wafer: chemically cleaning the surface of the epitaxial wafer, then placing the epitaxial wafer into an MOCVD reaction chamber, keeping the temperature at 700 ℃ and the pressure at 10Torr, and processing for 30 min;
s2, growing an ITO main body layer: under the protective atmosphere, adjusting the growth temperature to 530 ℃ and 600 ℃, adjusting the pressure of the reaction cavity to 6-15Torr, then introducing an indium source, a tin source and an oxygen source, adjusting the molar flow ratio of the flow control indium source to the tin source to be 5:1-50:1, adjusting the molar flow ratio of the flow control indium source to the oxygen source to be 1:500-1:3000, growing an ITO (indium tin oxide) main body layer with the thickness of 80-150nm on the surface of the pretreated epitaxial wafer, and controlling the growth speed to be 1-2 nm/min;
s3, growing an ITO coarsening layer: under the protective atmosphere, the growth temperature is adjusted to 380 ℃, the pressure of the reaction cavity is adjusted to 15Torr, then an indium source, a tin source and an oxygen source are introduced, the molar flow ratio of the indium source to the tin source is adjusted and controlled to be 5:1-50:1, the molar flow ratio of the indium source to the oxygen source is adjusted and controlled to be 1:1000-1:4000, an ITO rough layer with the thickness of 50-100nm is grown on the ITO main body layer, and the growth speed is controlled to be 2-5 nm/min.
4. The transparent electrode of claim 1, wherein the wavelength range of the GaN-based LED is 300-760 nm.
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