CN110230102B - Very low dislocation density gallium nitride single crystal and its flux method growth method - Google Patents
Very low dislocation density gallium nitride single crystal and its flux method growth method Download PDFInfo
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- CN110230102B CN110230102B CN201810179912.8A CN201810179912A CN110230102B CN 110230102 B CN110230102 B CN 110230102B CN 201810179912 A CN201810179912 A CN 201810179912A CN 110230102 B CN110230102 B CN 110230102B
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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
- C30B29/40—AIIIBV compounds wherein A is B, Al, Ga, In or Tl and B is N, P, As, Sb or Bi
- C30B29/403—AIII-nitrides
- C30B29/406—Gallium nitride
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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
- C30B9/00—Single-crystal growth from melt solutions using molten solvents
- C30B9/04—Single-crystal growth from melt solutions using molten solvents by cooling of the solution
- C30B9/08—Single-crystal growth from melt solutions using molten solvents by cooling of the solution using other solvents
- C30B9/12—Salt solvents, e.g. flux growth
Abstract
The invention discloses a method for growing gallium nitride single crystals with extremely low dislocation density by a fluxing agent method, which comprises the following steps: arranging a graphical mask on the gallium nitride substrate; growing and obtaining low dislocation density gallium nitride single crystal by using the gallium nitride substrate as seed crystal and utilizing a liquid phase epitaxy method; and carrying out dislocation selective etching on the low dislocation density gallium nitride single crystal, carrying out landfill treatment on the etched region to obtain a gallium nitride single crystal containing a landfill object, and growing by using a liquid phase epitaxy method to obtain the low dislocation density gallium nitride single crystal by taking the gallium nitride single crystal containing the landfill object as a seed crystal. Compared with the prior art, the method can obtain the gallium nitride single crystal with the extremely low dislocation density by utilizing a two-step method based on a flux method liquid phase epitaxial growth process, has simple and easy operation process and low cost, and can realize the large-scale production of the gallium nitride single crystal with the extremely low dislocation density.
Description
Technical Field
The invention relates to a preparation method of nitride single crystals, in particular to a method for growing gallium nitride single crystals with extremely low dislocation density by a fluxing agent method.
Background
The Flux method (Na Flux method) for growing gallium nitride (GaN) single crystals has many advantages, and is one of the internationally recognized growth techniques that can realize the industrial production of high-quality and large-size gallium nitride single crystals. The gallium nitride single crystal with low dislocation density is an important basic guarantee for obtaining high-performance and high-reliability gallium nitride photoelectric devices and microwave power devices. In the flux-method growth system, dislocations in the epitaxial gallium nitride crystal mainly come from the epitaxial substrate used in the initial stage of growth. Therefore, how to effectively achieve annihilation and suppression of growth of dislocations in the substrate during epitaxy is a key to obtaining a low dislocation density GaN single crystal. Seed crystals for the liquid phase epitaxial growth of gallium nitride single crystals by flux method, typically gallium nitride (GaN on SiC/Al) epitaxial on a foreign substrate2O3) Or fromSupporting gallium nitride (Freesenting-GaN), controlling growth conditions can realize that the gallium nitride mainly takes a three-dimensional island growth mode as a main growth stage in the growth stage, and further leading dislocations in the three-dimensional islands to be annihilated in an island combination mode, however, the mode only aims at high dislocation density (threading dislocation density is 10)6～108/cm2) The gallium nitride substrate of (2) is effective, and is not effective for a gallium nitride substrate having a low dislocation density.
Disclosure of Invention
The invention mainly aims to provide a gallium nitride single crystal with extremely low dislocation density and a growth method thereof by a flux method, so as to overcome the defects in the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
the embodiment of the invention provides a method for growing a gallium nitride single crystal with extremely low dislocation density by a fluxing agent method, which comprises the following steps:
arranging a graphical mask on the gallium nitride substrate;
growing the substrate of gallium nitride as a seed crystal by liquid phase epitaxy to obtain a low dislocation density (10)4～106cm-2) A gallium nitride single crystal;
carrying out dislocation selective corrosion on the low dislocation density gallium nitride single crystal, and carrying out landfill treatment on a corroded area to obtain the gallium nitride single crystal containing a landfill object; and
using gallium nitride single crystal containing filling material as seed crystal, utilizing liquid phase epitaxy method to grow and obtain very low dislocation density (10)2～104cm-2) A gallium nitride single crystal.
In some embodiments, the flux method for growing very low dislocation density gallium nitride single crystals specifically comprises: and carrying out dislocation selective etching on the low dislocation density gallium nitride single crystal, so that the threading dislocation region forms a hole structure, and the non-etched region is a threading dislocation free region or a low threading dislocation region.
Embodiments of the present invention also provide a very low dislocation density gallium nitride single crystal prepared by any of the foregoing methods.
Go toStep by step, the dislocation density in the extremely low dislocation density gallium nitride single crystal is 102～104cm-2。
Compared with the prior art, the method can obtain the gallium nitride single crystal with the extremely low dislocation density by utilizing a two-step method based on a flux method liquid phase epitaxial growth process, has simple and easy operation process and low cost, and can realize the large-scale production of the gallium nitride single crystal with the extremely low dislocation density.
Drawings
FIG. 1 is a schematic diagram of a process for growing a very low dislocation density gallium nitride single crystal by a flux method in an exemplary embodiment of the invention.
FIG. 2 is a cathode fluorescence (CL) test chart of a low dislocation density GaN single crystal obtained in an exemplary embodiment of the invention;
FIG. 3 is a cathode fluorescence test chart of a very low dislocation density gallium nitride single crystal obtained in an exemplary embodiment of the present invention.
Detailed Description
The inventors of the present invention found in long-term studies that in a system for liquid phase epitaxial growth of GaN by flux method, the lateral (a/m-direction) growth rate is faster than the epitaxial (c-direction) growth rate. Based on the characteristic of a flux method growth system, the inventor provides a method for growing a gallium nitride single crystal with extremely low dislocation density by a flux method, and the gallium nitride single crystal with extremely low dislocation density is obtained by a two-step method. In summary, the method of the present invention comprises: firstly, inhibiting dislocation in a gallium nitride substrate by using mask processing, and then obtaining gallium nitride single crystal by using liquid phase epitaxy; then dislocation selective etching is carried out on the gallium nitride single crystal, filling processing is carried out on the etched area, and finally the gallium nitride single crystal with extremely low dislocation density is obtained by utilizing liquid phase epitaxy.
More specifically, an aspect of the embodiments of the present invention provides a method for growing a very low dislocation density gallium nitride single crystal by a flux method, including:
arranging a graphical mask on the gallium nitride substrate;
the gallium nitride substrate is used as a seed crystal, and the low silicon nitride is obtained by growth by a liquid phase epitaxy methodDislocation density (10)4～106cm-2) A gallium nitride single crystal;
carrying out dislocation selective corrosion on the low dislocation density gallium nitride single crystal, and carrying out landfill treatment on a corroded area to obtain the gallium nitride single crystal containing a landfill object; and
using gallium nitride single crystal containing filling material as seed crystal, utilizing liquid phase epitaxy method to grow and obtain very low dislocation density (10)2～104cm-2) A gallium nitride single crystal.
Further, the material of the mask includes metal and/or metal compound (such as Ti or Ni or TiO)2Or SiO2Etc.). Furthermore, the thickness of the mask is preferably 1-100 μm.
In some embodiments, the method for growing very low dislocation density gallium nitride single crystals by flux method specifically comprises: subjecting the low dislocation density gallium nitride single crystal to dislocation selective etching so that the threading dislocation region forms a hole structure, and the non-etched region is a threading dislocation free region or a low threading dislocation region (dislocation density 10)4～105cm-2)。
Further, the low dislocation density gallium nitride single crystal may be subjected to dislocation selective etching using a chemical etching method.
Furthermore, the depth of the hole structure is preferably 10 to 500 μm.
In some embodiments, the flux method for growing very low dislocation density gallium nitride single crystals specifically comprises: and (5) burying the corrosion region by adopting an evaporation or spin coating mode.
Further, the material of the landfill includes metal and/or metal compound (for example, Ga or Al or GaCl)3Or AlCl3Etc.).
Further, the gallium nitride substrate comprises heteroepitaxy (e.g., GaN on SiC/Al)2O3) Or a homoepitaxial (GaN on GaN) gallium nitride substrate.
Another aspect of an embodiment of the present invention provides a very low dislocation density gallium nitride single crystal produced by any of the foregoing methods.
More specifically, referring to fig. 1, a method for growing a very low dislocation density gallium nitride single crystal by flux method according to an exemplary embodiment of the present invention is shown, which may include the following steps:
the first step is as follows: and growing the mask-processed gallium nitride single crystal. On a hetero-epitaxial or homo-epitaxial gallium nitride substrate, firstly, forming a patterned mask (the mask is a metal or a compound and has a height of 1-100 mu m) on the surface of the gallium nitride substrate in a photoetching or chemical deposition mode, and the dislocation of a part of the mask area is prevented from continuously growing upwards; and then, taking the processed gallium nitride substrate as a seed crystal, carrying out liquid phase epitaxial growth by adopting a fluxing agent method, and utilizing the lateral merging growth of the liquid phase epitaxial gallium nitride to realize merging annihilation of partial threading dislocation in the growth process of the gallium nitride without a mask area, thereby obtaining the liquid phase epitaxial gallium nitride single crystal with low dislocation density. The second step is that: dislocation selectively corroding the gallium nitride single crystal. Carrying out dislocation selective etching on the grown liquid phase epitaxial gallium nitride single crystal with low dislocation density by adopting a chemical etching means (such as molten KOH or molten NaOH or photoelectrochemical etching), so that a hole structure (with the depth of 10-500 mu m) is formed in a threading dislocation region, an un-etched region is a region without (or with little) threading dislocation, and the etched region is subjected to landfill treatment (a landfill is a metal or a compound) by adopting modes such as evaporation or spin coating; then, the treated gallium nitride single crystal is used as a seed crystal, and liquid phase epitaxial growth is carried out by adopting a fluxing agent method, so that the liquid phase epitaxial gallium nitride single crystal with extremely low dislocation density is obtained.
The technical solution of the present invention will be further explained with reference to the following examples.
The method for growing the gallium nitride single crystal with extremely low dislocation density by the flux method comprises the following steps:
the first step is as follows: setting patterned mask on gallium nitride substrate (homoepitaxy or heteroepitaxy GaN substrate grown on GaN substrate or sapphire or alumina substrate), wherein the mask pattern can be circular, diamond or other shape (diameter less than 50 μm, and material can be Ti, Ni, or TiO)2Or SiO2Etc.),and transferring the gallium nitride substrate serving as a seed crystal and growth raw materials into a crucible in a glove box, transferring the crucible into growth equipment, and growing by using a liquid phase epitaxy method to obtain the low dislocation density gallium nitride single crystal. Wherein a low dislocation density gallium nitride single crystal obtained after growth is subjected to chemical polishing treatment, then is corroded for 20 minutes at 240 ℃ by adopting molten KOH, and is characterized by a cathode fluorescence (CL) test on the corrosion pit density, wherein the dislocation density is about 4 multiplied by 105cm-2. The other low dislocation density gallium nitride single crystals obtained in this example also exhibited similar behavior, in which the dislocation density was controlled to 104～106cm-2Within the range of (1).
The second step is as follows: subjecting the low dislocation density gallium nitride single crystal (after cleaning and polishing) to dislocation selective etching, etching by using molten KOH or molten NaOH or photoelectrochemical etching to form a hole structure (with a depth of 10-500 mu m) in a threading dislocation region, and then using Ga or Al or GaCl3Or AlCl3And (3) performing landfill treatment on the corrosion area in a vapor deposition/spin coating mode to obtain gallium nitride single crystals containing landfill objects, transferring the gallium nitride single crystals containing the landfill objects as seed crystals into a crucible together with growth raw materials in a glove box, transferring the crucible into growth equipment, and growing by using a liquid phase epitaxy method to obtain the gallium nitride single crystals with extremely low dislocation density. Wherein a grown gallium nitride single crystal with extremely low dislocation density is subjected to chemical polishing treatment, then is corroded for 20 minutes at 240 ℃ by adopting molten KOH, and is characterized by a cathodic fluorescence (CL) test on the corrosion pit density, wherein the dislocation density is about 1 x 104cm-2. The other very low dislocation density GaN single crystals obtained in this example also exhibited similar behavior, in that the dislocation density was controlled to 104～105cm-2Within the range of (1).
In the first step and the second step, the process of liquid phase epitaxial growth of the gallium nitride single crystal specifically comprises: putting metal sodium, metal gallium, a carbon nitride additive (such as nitrided mesoporous carbon or graphite or graphene, the addition ratio of which is 0.005-1.0 mol% of the total amount of sodium and gallium) and seed crystals into a crucible in a glove box which is water-and oxygen-insulated, transferring the crucible into liquid phase epitaxial growth equipment, and carrying out liquid phase epitaxial growth of gallium nitride single crystals by a fluxing agent method under the conditions of 3-10 MPa pressure and 700-1000 ℃. It should be understood that the above-mentioned embodiments are merely illustrative of the technical concepts and features of the present invention, which are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and therefore, the protection scope of the present invention is not limited thereby. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (4)
1. A method for growing gallium nitride single crystal with extremely low dislocation density by flux method is characterized by comprising:
arranging a graphical mask on the gallium nitride substrate;
growing and obtaining the low dislocation density gallium nitride single crystal by using the gallium nitride substrate as a seed crystal and utilizing a liquid phase epitaxy method, wherein the dislocation density in the low dislocation density gallium nitride single crystal is 104~106cm-2；
Carrying out chemical polishing treatment on the low dislocation density gallium nitride single crystal, carrying out dislocation selective corrosion on the low dislocation density gallium nitride single crystal by adopting molten KOH or molten NaOH to enable a hole structure with the depth of 10-500 mu m to be formed in a threading dislocation area, enabling an area which is not corroded to be a threading dislocation area or a low threading dislocation area, and then carrying out landfill treatment on the corrosion area by adopting an evaporation or spin coating mode to obtain the gallium nitride single crystal containing a landfill object, wherein the landfill object is made of metal and/or metal compound, the metal is Ga or Al, and the metal compound is GaCl3Or AlCl3(ii) a And
taking gallium nitride single crystal containing landfill as seed crystal, and growing by using a liquid phase epitaxy method to obtain the gallium nitride single crystal with extremely low dislocation density, wherein the dislocation density in the gallium nitride single crystal with extremely low dislocation density is 102~104cm-2。
2. The flux method according to claim 1A method for growing a gallium nitride single crystal with a very low dislocation density, characterized in that: the mask is made of Ti, Ni and TiO2Or SiO2。
3. The flux-assisted method of growing very low dislocation density gallium nitride single crystals according to claim 1, wherein: the thickness of the mask is 1-100 μm.
4. The flux-assisted method of growing very low dislocation density gallium nitride single crystals according to claim 1, wherein: the gallium nitride substrate comprises a heteroepitaxial or homoepitaxial gallium nitride substrate.
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| WO2001075952A1 (en) * | 2000-03-31 | 2001-10-11 | Toyoda Gosei Co., Ltd. | Production method of iii nitride compound semiconductor and iii nitride compound semiconductor element |
| CN1870223A (en) * | 1999-09-28 | 2006-11-29 | 住友电气工业株式会社 | Crystal growing method for single-crystal gan, and single-crystal gan substrate and manufacturing method thereof |
| CN103247724A (en) * | 2012-02-08 | 2013-08-14 | 郭磊 | Semiconductor structure and forming method thereof |
| CN106435720A (en) * | 2016-09-22 | 2017-02-22 | 东莞市联洲知识产权运营管理有限公司 | Preparation method of GaN film material |
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| US7556687B2 (en) * | 2001-09-19 | 2009-07-07 | Sumitomo Electric Industries, Ltd. | Gallium nitride crystal substrate and method of producing same |
| JP2009167053A (en) * | 2008-01-16 | 2009-07-30 | Sumitomo Electric Ind Ltd | Method for growing group iii nitride crystal |
| CN102409406A (en) * | 2011-10-28 | 2012-04-11 | 中国科学院半导体研究所 | Growing method for low-dislocation gallium nitride |
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| CN1870223A (en) * | 1999-09-28 | 2006-11-29 | 住友电气工业株式会社 | Crystal growing method for single-crystal gan, and single-crystal gan substrate and manufacturing method thereof |
| WO2001075952A1 (en) * | 2000-03-31 | 2001-10-11 | Toyoda Gosei Co., Ltd. | Production method of iii nitride compound semiconductor and iii nitride compound semiconductor element |
| CN103247724A (en) * | 2012-02-08 | 2013-08-14 | 郭磊 | Semiconductor structure and forming method thereof |
| CN106435720A (en) * | 2016-09-22 | 2017-02-22 | 东莞市联洲知识产权运营管理有限公司 | Preparation method of GaN film material |
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