CN102418143A

CN102418143A - Method for preparing self-stripping GaN single crystal from H3PO4 corrosion substrate

Info

Publication number: CN102418143A
Application number: CN2011103663417A
Authority: CN
Inventors: 郝霄鹏; 邵永亮; 张雷; 吴拥中; 张浩东
Original assignee: Shandong University
Current assignee: Shandong University
Priority date: 2011-11-17
Filing date: 2011-11-17
Publication date: 2012-04-18

Abstract

The invention provides a method for preparing a self-stripping GaN single crystal from an H3PO4 corrosion substrate. The method comprises the following steps of: firstly, epitaxially growing a GaN film with the thickness of 2-10mu m on a sapphire substrate by using a metal organic chemical deposition method and forming a GaN epitaxial wafer; secondly, immersing the GaN epitaxial wafer into an H3PO4 solution with the temperature of 220-280DEG C and the concentration of 70-90 percent and corroding for 3-30 minutes; thirdly, quickly taking the corroded GaN epitaxial wafer out of the H3PO4 solution and placing the taken GaN epitaxial wafer into cold water for stopping corrosion; fourthly, cleaning and blowing the corroded GaN epitaxial wafer to be dry and placing the dry GaN epitaxial wafer into a hydride vapor phase epitaxial growth system for epitaxially growing the GaN single crystal; and fifthly, after the GaN single crystal is epitaxially grown, realizing self stripping of the GaN single crystal from the sapphire substrate through the temperature reduction process of the hydride vapor phase epitaxial growth system to obtain a self-supported GaN single crystal. The method has the characteristics of low cost, simpleness and feasibility and is suitable for batch production.

Description

A kind of with H 3PO 4The corrosion substrate preparation is from the method for peeling GaN monocrystalline

Technical field

The present invention relates to a kind of method for preparing self-stripping gallium nitride (GaN) monocrystalline, belong to the photoelectron technology field.

Background technology

With gan (GaN) is the third generation semiconductor material of representative, because of the extensive concern of its excellent properties that has because of its investigator.Gan is different from the first-generation and the most important physical characteristics of s-generation semiconductor material is to have wideer forbidden band (at room temperature its energy gap is 3.4eV), can the emission wavelength blue light shorter than ruddiness.Simultaneously it also has characteristics such as high-breakdown-voltage, high electron mobility, chemical property be stable, high temperature resistant, corrosion-resistant, therefore is fit to very much making radioprotective, high frequency, high-power and superintegrated electron device and indigo plant, green glow and ultraviolet photoelectron device.Therefore, the research of GaN semiconductor material and application become the forward position and the focus of present global semiconductor research.

In order to reduce the stress that lattice mismatch and thermal mismatching are brought, and further obtain high quality self-supporting GaN single crystalline substrate material, the investigator attempted multiple HVPE (hydride gas-phase epitaxy) growth substrates treatment process.Domestic method is to use laser lift-off technique, and the GaN that thickness is bigger peels off from Sapphire Substrate.But this kind method needs big thickness high quality flawless HVPE-GaN, and this has certain difficulty to hetero epitaxy GaN on Sapphire Substrate.Through before growing substrate is handled, reduced the stress that mismatch is brought, and in temperature-fall period, realize peeling off of HVPE-GaN and substrate, this application also very extensively.In general the purpose that common treatment process will reach is between substrate and HVPE growing GaN, to add supple buffer layer [Hyun-Jae Lee, et al, Applied Physics Letter 91 (2007) 192108]; Or leave space [Y.Oshima; Et al, phys.stat.sol. (a), 194 (2002) 554-558]; Or utilize periodicity nano graph substrate to reduce GaN and substrate contact area (C.L. Chao, Appl.Phys.Lett.95 (2009) 051905).These methods can help HVPE (hydride gas-phase epitaxy) growing GaN in temperature-fall period, from substrate, to obtain self-supporting GaN single crystalline substrate from peeling off.But these methods need multistep technologies such as complicated photoetching, growth when the preparation growth substrates.

Summary of the invention

The present invention is directed to the deficiency that existing GaN single crystal preparation technology exists, provide a kind of prepare that process is simple, cost is low with H ₃PO ₄The corrosion substrate preparation is from the method for peeling GaN monocrystalline, and this method utilization simple goes on foot H ₃PO ₄Caustic solution is handled MOCVD-GaN/Al ₂O ₃Substrate reaches corrosion N face MOCVD-GaN effect, on N face GaN, produces the dodecahedron pyramidal structure.

Of the present invention with H ₃PO ₄The corrosion substrate preparation may further comprise the steps from the method for peeling GaN monocrystalline:

(1) utilizes method thick GaN film of epitaxy 2 μ m-10 μ m on Sapphire Substrate of metal organic chemical vapor deposition (MOCVD), form the GaN epitaxial wafer;

(2) the GaN epitaxial wafer being immersed temperature is that 220-280 ℃, concentration are the H of 70%-90% ₃PO ₄Corrosion is 3 minutes-30 minutes in the solution;

(3) the corrosion after the GaN epitaxial wafer from H ₃PO ₄Take out rapidly in the solution and put into cold water to stop corrosion;

(4) after the GaN epitaxial wafer after will corroding cleans, dries up, put into hydride gas-phase epitaxy (HVPE) growing system epitaxy GaN monocrystalline;

(5) epitaxy GaN monocrystalline finishes after the temperature-fall period of perhydride vapour phase epitaxy (HVPE) growing system, and the GaN monocrystalline is realized on the Sapphire Substrate obtaining self-supporting GaN monocrystalline from peeling off.

In the said process, epitaxial wafer corrosion rear section GaN film is penetrated, and forms the sexangle corrosion pit, and the sexangle corrosion pit is interconnected to form erose large-scale corrosion pit.After the N face that the GaN film contacts with sapphire is corroded by SPA, show two cover family of crystal planes according to different crystal face erosion rate differences, demonstrate 12 faces altogether, formation has dodecahedro awl accumulative structure.This substrate is filled through the maximum corrosion pit in HVPE growth back, and leaves the space between the dodecahedro wimble structure, has blocked the extension of dislocation, for stress relief has flowed out the space.Because the summit of dodecahedro awl towards Sapphire Substrate, has reduced the contact area between GaN and the Sapphire Substrate, when HVPE-GaN thickness is enough big, can realize that the cooling back obtains self-supporting GaN monocrystalline from peeling off simultaneously.

The present invention has low, the simple characteristics of cost, is suitable for producing in batches.

Description of drawings

Fig. 1 is the schema of the inventive method.

Fig. 2 is the schematic diagram of the inventive method.

Fig. 3 is the H that the present invention makes ₃PO ₄Corrosion substrate surface pattern sem (SEM) image.

Fig. 4 is the H that the present invention makes ₃PO ₄The N face of corrosion substrate GaN forms dodecahedro cone structure sem (SEM) image.

Fig. 5 is self-supporting GaN monocrystalline N face pattern sem (SEM) image that the present invention prepares.

Wherein: 1, Sapphire Substrate, 2, the GaN film, 3, the GaN film after the corrosion, 4, HVPE Grown GaN monocrystalline.

Embodiment

Of the present invention with H ₃PO ₄The corrosion substrate preparation is to adopt H from the method for peeling GaN monocrystalline ₃PO ₄Corrosion MOCVD growing GaN thin film epitaxy sheet prepares and has N face corrosion dodecahedro cone structure substrate, and Fig. 1 and Fig. 2 have provided concrete preparation process:

(1) utilizing MOCVD method epitaxy thickness on Sapphire Substrate 1 is the GaN film 2 of 3 μ m-5 μ m, referring to (a) among Fig. 2 figure, forms the GaN epitaxial wafer;

(2) concentration with 220-280 ℃ of MOCVD Grown GaN epitaxial wafer immersion is the H of 70%-90% ₃PO ₄Corrosion is 3 minutes-30 minutes in the solution;

(3) the corrosion after the GaN epitaxial wafer from H ₃PO ₄Take out rapidly in the solution and put into cold water to stop its corrosion, the GaN film 3 after obtaining corroding (referring to (b) among Fig. 2 figure).This moment, part GaN film was penetrated, and formed large-scale irregular shape corrosion pit, and its pattern is as shown in Figure 3.The GaN film is corroded with the N face (the N face of GaN film is meant that one side that is connected with Sapphire Substrate 1) of Sapphire Substrate contact and forms the dodecahedro cone structure, and structure and morphology is as shown in Figure 4.

(4) with the GaN epitaxial wafer after the above-mentioned corrosion through washed with de-ionized water, dry up after, put into HVPE growing system epitaxy GaN monocrystalline 4, scheme referring to (c) among Fig. 2.

(5) after epitaxy GaN monocrystalline 4 finished, through the temperature-fall period of HVPE, GaN monocrystalline 4 was realized on Sapphire Substrate 1, peeling off certainly, obtains the GaN monocrystalline of self-supporting.Pattern sem (SEM) image of self-supporting GaN monocrystalline N face is as shown in Figure 5.

Above-mentioned employing H ₃PO ₄Corrode substrate Grown GaN monocrystalline, reduced the contact area of GaN and Sapphire Substrate, reserve the space and discharge stress.When the HVPE growth thickness is big, can realize obtaining the GaN monocrystalline from peeling off.

Claims

1. one kind with H ₃PO ₄The corrosion substrate preparation is characterized in that from the method for peeling GaN monocrystalline, may further comprise the steps:

(1) utilizes method thick GaN film of epitaxy 2 μ m-10 μ m on Sapphire Substrate of metal organic chemical vapor deposition, form the GaN epitaxial wafer;

(4) after the GaN epitaxial wafer after will corroding cleans, dries up, put into the epitaxy GaN of hydride gas phase epitaxial growth system monocrystalline;

(5) epitaxy GaN monocrystalline finishes after the temperature-fall period of perhydride vapor phase epitaxial growth system, and the GaN monocrystalline is realized on the Sapphire Substrate obtaining self-supporting GaN monocrystalline from peeling off.