JP4815569B2 - Method for growing gallium nitride crystal on Si substrate crystal - Google Patents

Description

  The present invention relates to a method for crystal growth of gallium nitride (GaN) on a silicon substrate and related technology.

  GaN (gallium nitride) is widely used as a material for light emitting diodes.

  MOVPE (Metalorganic Chemical Vapor Phase Deposition) is known as one of the methods for growing GaN crystals, and has been widely used. When GaN is crystal-grown by this MOVPE method, a sapphire substrate or a silicon carbide (SiC) substrate has been used as a substrate (referred to as substrate crystal) as a base for the crystal growth.

  Since these substrates are very expensive, the use of inexpensive silicon substrates has long been considered.

Silicon substrate
However, it is known that when a GaN crystal is grown by the MOVPE method using this silicon substrate, it is difficult to continue high-quality crystal growth for a long time. The reason is considered to be that the source gas reacts with silicon.

  Further, for example, “http://www.sanken-ele.co.jp/news/contents/20011122.htm” (Sanken Electric, NEWS release) (Non-patent Document 3) on the Internet has these problems. Are listed. This Non-Patent Document 3 also describes a method for solving the above problems.

  According to this description, firstly, in order to suppress the reaction between silicon and the GaN material, it is proposed that the silicon surface before epitaxial growth is made flat in atomic order and covered with hydrogen atoms. Yes. Second, in order to improve the crystallinity of GaN, it has been proposed to investigate various plane orientations of the silicon substrate and adopt the Si (111) plane having the best crystallinity. It is described that the general technical common sense that it is difficult to directly grow GaN crystals on a silicon substrate because Si and Ga react by such a method is described.

  As described above, it is difficult to grow a GaN crystal using a silicon substrate. It is known that when a GaN buffer layer is formed on a silicon substrate, irregularities and holes are formed on the substrate. This reason was thought to be because Si and Ga would react. This problem is also described in Non-Patent Document 1, for example. A photograph showing the state of the “hole” described in Non-Patent Document 1 is cited and published in FIG.

Improved GaN crystal growth according to the prior art Accordingly, it is difficult to employ a buffer layer by GaN, in recent years, the use of a buffer layer by AlN has become common.

  The state of crystal growth of GaN when using a buffer layer of AlN is shown in FIG. As shown in this figure, an AlN buffer layer is first provided at a low temperature on a silicon substrate as shown in FIG. 11 (1) (FIG. 11 (2), and then GaN crystal growth is performed at a high temperature. (FIG. 11 (3)).

Other conventional techniques Various techniques are known for crystal growth of GaN.

  (A) For example, a technique for depositing GaN on GaAs is known. In this technique, it can be said that it is preferable to grow GaN on the surface where arsenic is easily removed in consideration of the “front” and “back” surfaces of the GaAs crystal surface (111). Such a technique is described in Non-Patent Document 2 below.

  (B) Patent Document 1 below discloses a configuration in which a titanium nitride film is provided on a silicon substrate and GaN is stacked thereon.

  (C) Moreover, the following patent document 2 discloses a technique for providing irregularities on a silicon substrate. By this unevenness, even if GaN is directly grown without providing a low-temperature GaN buffer layer, it is possible to suppress the lateral growth of the crystal and to realize a flat crystal growth.

  (D) Patent Document 3 below discloses a technique for growing a III-V nitride (particularly GaN) crystal using a silicon substrate on which a natural oxide film is formed. Patent Document 3 discloses a technique in which the natural oxide is nitrided and converted to a SiON film, and then a III-V nitride (particularly GaN) is crystal-grown on the SiON film.

  (E) Patent Document 4 listed below describes a technique comprising two stages of growth as a method for growing a nitride semiconductor crystal. First, in the first stage, island-like crystal regions are formed on a substrate (base) at a low crystal growth rate at a low temperature. In the second stage, a technique is disclosed in which crystal growth is performed at a high temperature and a high crystal growth rate so as to bond island-like crystal regions.

  (F) In Patent Document 5 below, a GaN amorphous layer is formed on a base plate made of GaN single crystal, and a GaN single crystal layer is further formed on the amorphous layer. A description is disclosed. It is said that crystal defects such as dislocations are reduced.

  (G) In Patent Document 6 below, a 3C—SiC single crystal layer and a BGaN mixed crystal layer are sequentially provided on a single crystal silicon substrate. Then, a c-GaN single crystal film is formed on these. It is described that a GaN semiconductor capable of controlling defects can be obtained.

  (H) Patent Document 7 below discloses a technique in which a c-BP film is formed as a buffer layer on a silicon substrate, and 3C-SiC or c-GaN is epitaxially grown on the buffer layer. Yes. It is described that the problem of lattice mismatch can be solved. Also disclosed is a technique for forming an amorphous SiC or GaN film at 300 ° C. to 600 ° C. on the c-BP buffer layer.

JP 2000-031534 A (Sunken) JP 2002-289540 A (Mitsubishi Electric Cable) Japanese Patent Laid-Open No. 10-163528 (Furukawa Electric) JP 2002-313733 A (Sony) JP 2000-340509 A (Sumitomo Electric Industries) JP-A-2005-32766 (Toshiba Ceramics) JP 2004-22581 A (Toshiba Ceramics) A. Dadgar, M. Poscherieder, J. Blasing, et al., "MOVPE growth of GaN on Si (111) substrates", J. of Crystal Growth 248 (2003), pp556-562 Yoshinao Kumagai, Akinori Koukitu, Hisashi Seki, "Investigation of Substrate Orientation Dependennce for the Growth of GaN on GaAs (111) A and (111) B Surfaces by Metalorganic Hydrogen Chloride Vapor-phase Epitaxy", Jpn. J. Appl. Phys. , Vol.39 (2000), pp.L149-L151, Part2, No.2B, 15 February 2000 "Development of GaN-based high-efficiency blue LED using silicon substrate", NEWS release, November 2001, Sanken Electric, [Search February 8, 2005], Internet <URL: http: //www.sanken- ele.co.jp/news/contents/20011122.htm>

  As described above, there are various attempts to perform GaN crystal growth on a silicon substrate, but these have the following problems.

  (1) In the technique of using AlN or other substances as a buffer layer, the material used increases, and the apparatus tends to be complicated. In addition, since the types of materials increase, the management cost of the materials also increases.

  (2) Further, in the method of processing on the surface of the silicon substrate, it is necessary to process the surface to “roughen”, which may cause a problem in flatness. Moreover, the process for a process is needed and there exists a possibility that the crystal growth method may become complicated.

  Therefore, a technique capable of growing a high-quality GaN crystal on a silicon substrate by a simpler technique is widely desired.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for growing GaN crystals on a silicon substrate without complicated processing.

  As described above, silicon substrates (Si substrates) are widely available as large substrate crystals in the world, so that if they can be used as substrates, it is possible to manufacture optical elements and electronic devices at a very low cost. Therefore, as already described, many studies have been made on crystal growth of GaN on a silicon substrate.

  As described above, when GaN is epitaxially grown on Si under normal conditions, a hole-like defect occurs at the GaN-Si interface, and good crystal growth of GaN cannot be achieved. There have been many reports (dissertations and academic presentations) that capture this phenomenon and generally cause a reaction between the substrate Si and the Ga molecular species as the raw material.

  Currently, one of the most representative techniques for solving this problem would be the use of the buffer layer described above. That is, an AlN thin film (buffer layer) is first grown on a Si substrate, and then GaN is grown. LEDs are actually made using this technology and are commercially available. This is described in Non-Patent Document 3 above.

By the way, the inventors of the present application have studied for a long time a method of growing GaN on a Si substrate without using a material other than a GaN raw material such as Al. In particular, after a GaN buffer layer was provided on a silicon substrate, intensive research was conducted on a technique for crystal growth of GaN thereon.

  As a result, the inventors of the present application normally do not react Si and Ga raw materials but cause defects such as holes in the silicon substrate when GaN is directly grown on a silicon substrate. It was found that hydrogen in the gas phase atmosphere was adsorbed on the outermost surface of Si and the adsorbed hydrogen hindered the growth of GaN.

And it is thought that a hole is opened in this layer by preventing the growth of the GaN buffer layer. The inventors of the present invention have clarified that NH ₃ and Si, which are raw materials, react through the hole during GaN growth at high temperature, and the interface becomes uneven.

  Through these studies, the inventors of the present application, after growing hydrogen adsorbed on Si in a hydrogen-free (or sufficiently small) atmosphere in order to grow GaN directly on the Si substrate, The inventors have invented a method of growing a buffer layer and then epitaxially growing GaN.

  According to this method, a good quality GaN crystal can be obtained. The inventors of the present application actually executed this method and grown GaN on a Si substrate to obtain a GaN crystal. This GaN crystal was confirmed to be a good quality GaN crystal capable of PL emission.

  Specifically, the present invention employs the following means.

  (1) In order to solve the above-described problems, the present invention provides a method for crystal growth of gallium nitride on a silicon substrate, a hydrogen desorption step for desorbing hydrogen atoms on the silicon substrate, and the hydrogen desorption step. And a buffer layer forming step of forming a buffer layer on the silicon substrate; and a crystal growth step of crystal growing gallium nitride on the buffer layer. It is.

  As described above, since hydrogen atoms on the silicon substrate are desorbed, it is possible to prevent hydrogen from interfering with the crystal growth of GaN. As a result, a buffer layer without a flat hole can be formed. Further, if gallium nitride crystal growth is performed thereon, a high-quality gallium nitride crystal can be obtained.

  (2) Further, in the gallium nitride crystal growth method according to the above (1), the hydrogen desorption step includes a step of heating the silicon substrate to a temperature of 700 ° C. or higher. This is a gallium nitride crystal growth method.

  Hydrogen can be eliminated by heating. The heating temperature is more preferably 800 ° C. or higher, and even more preferably 900 ° C. or higher.

  (3) Further, according to the present invention, in the gallium nitride crystal growth method according to (1), the hydrogen desorption step includes a step of placing the silicon substrate in a nitrogen atmosphere at a temperature of 700 ° C. or higher. This is a characteristic gallium nitride crystal growth method.

  When heating, under a nitrogen atmosphere not containing hydrogen, it is possible to prevent hydrogen from being bound (terminated) to the surface again. The temperature in the nitrogen atmosphere is more preferably 800 ° C. or higher, and even more preferably 900 ° C. or higher.

  (4) Further, according to the present invention, in the gallium nitride crystal growth method according to (1), the hydrogen desorption step includes a step of placing the silicon substrate in an inert gas atmosphere having a temperature of 700 ° C. or higher. This is a method for growing a gallium nitride crystal.

  When heating is performed in an inert gas atmosphere containing no hydrogen, it is possible to prevent hydrogen from being bonded (terminated) to the surface again. The temperature of the inert gas is more preferably 800 ° C. or higher, and even more preferably 900 ° C. or higher.

(5) Furthermore, the present invention provides the gallium nitride crystal growth method according to the above (1),
The buffer layer forming step is a gallium nitride crystal growth method characterized in that it includes a step of forming a buffer layer under an atmosphere containing no hydrogen.

  By forming the buffer layer under an atmosphere containing no hydrogen, a flatter buffer layer can be formed.

  (6) Moreover, this invention is a gallium nitride crystal growth method as described in any one of said (1)-(5), The said buffer layer in the said buffer layer formation process is a gallium nitride buffer layer. This is a method for growing a gallium nitride crystal.

  With such a configuration, since there is no interference by hydrogen atoms when forming the gallium nitride buffer layer, it is possible to form a buffer layer that is flatter and has no holes.

  As described above, according to the present invention, since hydrogen atoms are desorbed from the surface of the silicon substrate, it is easier to form the buffer layer, and the flatness of the buffer layer is improved. As a result, a higher quality GaN crystal can be grown.

  In particular, if a GaN buffer layer is used as the buffer layer, there is no need to prepare another type of source gas such as Al as the buffer layer, which is a simpler method than the method using Al or the like as the buffer layer. A GaN crystal can be obtained.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In this embodiment, as a method for growing a GaN crystal on a silicon substrate, a preferred embodiment of a technique for performing GaN epitaxial growth after providing a GaN buffer layer on the silicon substrate will be described.

As described in Chapter 1 Principle Background Art, when a GaN buffer layer is formed on a silicon substrate, it is known that the surface flatness is lost, for example, there is a hole in the substrate surface. As a result, even if a GaN crystal was epitaxially grown on the GaN buffer layer, a good quality GaN crystal could not be obtained. Conventionally, it has been generally accepted that Si and Ga react with each other, for example, because there is a hole in the substrate surface.

  The inventor of the present application considered that this general theory is not necessarily a valid reason, and thought that the cause of the occurrence of holes and the like was hydrogen atoms existing on the surface of the silicon substrate. And we were able to confirm the validity of this idea through experiments.

The result of this experiment is shown in FIG. FIG. 1 is a SEM (scanning electron microscope) photograph showing the state of the silicon substrate surface when a GaN buffer layer is provided on the silicon substrate. The film formation conditions for these GaN buffer layers are: a gas atmosphere in which the partial pressure of TMG gas is 2.0 × E-5 atm, the partial pressure of NH ₃ gas is 0.2 atm, and the temperature is 640 ° C. The film was formed. The total pressure of this gas is 1 atm. This condition is common to FIGS. 1 (1), (2), and (3).

  The difference between (1), (2) and (3) in FIG. 1 is the carrier gas used.

FIG. 1 (1) is an example using a carrier gas that is all N ₂ . In this embodiment, the hydrogen partial pressure ratio in the carrier gas is referred to as “F”. That is, in FIG. 1 (1), F = 0 (hydrogen partial pressure ratio is 0).

  As shown in FIG. 1A, it is clearly shown that the GaN buffer layer covers the entire surface of the silicon substrate at the hydrogen partial pressure ratio F = 0.

Next, in FIG. 1 (2), N ₂ + H ₂ was used as a carrier gas. In this case, the hydrogen partial pressure ratio F = 0.1. That is, this is an example using a carrier gas containing 10% hydrogen.

  As shown in FIG. 1B, at the hydrogen partial pressure ratio F = 0.1, although the GaN buffer layer covers the silicon substrate surface, there are some places where the silicon substrate is partially exposed. . Thus, it is clear from the photograph that the GaN buffer layer has holes partially opened.

Next, in FIG. 1 (3), H ₂ was used as a carrier gas. In this case, since the carrier gas is all hydrogen gas, the hydrogen partial pressure ratio F = 1.0.

  As shown in FIG. 1 (3), when the hydrogen partial pressure ratio is F = 1.0, only the GaN buffer layer is scattered in an island shape on the surface of the silicon substrate, so that most of the silicon substrate is exposed without being covered. It is in a state of being. Thus, the GaN buffer layer is hardly formed.

  From these facts, it is clear that the surface homology of the GaN buffer layer depends on the hydrogen partial pressure. Then, it was found that the formation of the GaN buffer layer is hindered when hydrogen is contained in the apparatus system during film formation (specifically, in the carrier gas) even at only 10 percent.

As a result, the present inventors have realized a new GaN crystal growth method characterized by forming a GaN buffer layer using a carrier gas having a hydrogen gas partial pressure ratio of 0.

  A conceptual diagram of a GaN crystal growth method described in the present embodiment is shown in FIG. First, in FIG. 2A, the surface of the silicon substrate 2 is terminated with hydrogen. Next, in FIG. 2 (2), this hydrogen is desorbed. This point is characteristic in the present embodiment. Then, the GaN buffer layer 4 is laminated on the surface from which hydrogen has been removed. Then, GaN is epitaxially grown on the GaN buffer layer to form a GaN crystal layer 6.

Chapter 2 Specific Example Based on the principle described in Chapter 1, a specific processing flow for actually growing a GaN crystal will be described.

2.1 Apparatus Configuration FIG. 3 shows a configuration diagram of a GaN crystal growth apparatus 10 that performs GaN crystal growth in this embodiment. As shown in this figure, the GaN crystal growth apparatus 10 includes a quartz reaction tube 12 for crystal growth. A carbon susceptor 16 for placing a substrate crystal 14 is provided in the quartz reaction tube 12, and an RF coil 18 for heating the carbon susceptor 16 is provided around the quartz reaction tube 12. Yes. By passing a high-frequency current through the RF coil 18, an induced current is generated in the carbon susceptor 16, and the substrate crystal 14 placed thereon is heated by heating the carbon susceptor 16.

Further, the GaN crystal growth apparatus 10 is provided with N ₂ sources 20a and 20b and H ₂ sources 22a, 22b and 22c in order to supply a carrier gas to the quartz reaction tube 12. These are supplied to the quartz reaction tube 12 via predetermined flow control devices 24a, 24b, 24c, 24d, 24e, valves 26a, 26b, 26c, 26d, 26e, and the like. The quartz reaction tube 12 is provided with an exhaust port 12b for exhausting carrier gas and source gas.

Further, the GaN crystal growth apparatus 10 is provided with a TMG source 28 and an NH ₃ source 30 in order to supply a raw material gas to the quartz reaction tube 12. Here, TMG is Tri-Methyl Gallium. The TMG gas generated by the TMG source 28 is supplied to the quartz reaction tube 12 by being mixed into the carrier gas via the flow rate control device 24d and the valve 26c. Moreover, NH NH ₃ source 30 supplies _3, a flow control device 24e, a valve 26e, by incorporating into the carrier gas through a 26 g, fed in the quartz reaction tube 12. TMG gas is discharged to the outside through the valve 26d as necessary, and NH ₃ is also discharged to the outside through the valve 26f as necessary.

  The silicon substrate 14 placed on the carbon susceptor 16 is a silicon substrate 14 having a (111) plane.

Thus, in the present embodiment, TMG is used as a group III element material, and NH ₃ is used as a group V element material.

2.2 Operation of crystal growth Crystal growth of GaN is performed using a crystal growth apparatus 10 as shown in FIG. Changes in temperature and carrier gas at that time are shown in the graph of FIG. In the graph of FIG. 4, the horizontal axis represents elapsed time (minutes), and the vertical axis represents temperature (° C.).

As shown in this graph, the silicon substrate 14 is first cleaned with HF, and immediately after cleaning, the surface of the silicon substrate is terminated with hydrogen atoms. The temperature is increased from this state to 250 ° C., and the carbon susceptor 16 is preheated. Carrier gas used at this time is H _2.

After heating at 250 ° C. for 10 minutes (indicated by the elapsed time of 5 to 15 minutes in the graph) and preheating the carbon susceptor 16, the temperature is raised to 950 ° C. (at the time of 20 minutes in the graph) and terminating. Desorb hydrogen atoms. As a result, a clean Si surface can be formed. When heating at 950 ° C. is continued for 15 minutes (at 35 minutes in the graph), the carrier gas is replaced with N _{2 so} that new hydrogen atoms do not terminate on the surface. After heating at 950 ° C. for another 10 minutes (at 45 minutes in the graph), the temperature is lowered to maintain the GaN buffer layer formation temperature (after 50 minutes in the graph).

In addition, the process of raising the temperature to 950 ° C. and desorbing hydrogen atoms in this way corresponds to a preferred example of the hydrogen desorption process in the claims. In particular, the step of heating by replacing the carrier gas with N ₂ (period from 35 minutes to 45 minutes in the graph) is an important point in the present embodiment. Since it is replaced with N ₂ , hydrogen does not terminate on the Si surface even if the temperature is lowered.

In forming the GaN buffer layer, N ₂ gas is used as the carrier gas. At this time, source gas is also introduced. As for the ratio of this source gas, TMG is 2.0E-5 atm and NH ₃ is 0.2 atm. The ratio of both is 10,000. Further, the total flow rate of the gas when forming the GaN buffer layer is 1750 sccm. The formation temperature of the GaN buffer layer may be set similarly to the conventional one. Generally, a range of 500 ° C. to 700 ° C., for example, 640 ° C. is preferable, but other temperatures may be used.

Thus, since a flat GaN buffer layer without a hole was formed, a good quality GaN crystal can be grown by epitaxially growing GaN thereon.

2.3 Obtained GaN Crystal The inventors of the present invention actually grown a GaN crystal on such a flat GaN buffer layer having no holes to obtain a good quality GaN crystal.

The parameters for growing this GaN crystal are that the partial pressure of TMG is 4.0E-5 atm and the partial pressure of NH ₃ is 0.2 atm. The crystal growth temperature is 1050 ° C., and the carrier gas is H ₂ . The parameters for forming the GaN buffer layer are that the partial pressure of TMG is 2.0E-5 atm and the partial pressure of NH ₃ is 0.2 atm. The formation temperature of the GaN buffer layer is 640 ° C., and the carrier gas is N ₂ .

  The X-ray diffraction pattern was measured for the GaN crystal thus grown on the silicon substrate. The result is shown in FIG. FIG. 5 is a measurement graph of an X-ray diffraction pattern, in which the horizontal axis represents angle (degrees) and the vertical axis represents signal intensity (arbitrary unit). As is clear from this graph, the intensity peak of the Si substrate (111) surface and the intensity peak of GaN (0002) were observed, and other characteristic peaks were not observed. Further, a PL light emitting element was constructed using this GaN crystal, and the light emission characteristics were measured. A graph representing the result is shown in FIG. The vertical axis of this graph is signal intensity (arbitrary unit), and the horizontal axis is wavelength. As shown in this graph, it was possible to emit ultraviolet light having a strong peak at 363.1 nm. Further, an SEM photograph showing a cross-sectional view of the obtained GaN crystal is shown in FIG. It will be understood that a GaN buffer layer is formed on a silicon substrate and a GaN crystal is stacked thereon.

2.4 Comparative example (when carrier gas is H ₂ only)
For comparison with the example described in 2.3 above, an example in which a GaN crystal is grown using a conventional technique is shown.

Based on the conventional general technique, the partial pressure of TMG was set to 2.0E-5 atm and the partial pressure of NH ₃ was set to 0.2 atm as parameters when the GaN buffer layer was formed. The formation temperature of the GaN buffer layer was 640 ° C., and H ₂ was used as the carrier gas. After forming the GaN buffer layer under such conditions, a GaN crystal was grown thereon. The parameters at this time are such that the partial pressure of TMG is 4.0E-5 atm and the partial pressure of NH ₃ is 0.2 atm. The crystal growth temperature is 1050 ° C., and the carrier gas is only H ₂ .

  The X-ray diffraction pattern of the GaN crystal thus grown on the silicon substrate was measured in the same manner as 2.3. The result is shown in FIG. FIG. 8 is a measurement graph of an X-ray diffraction pattern, in which the horizontal axis represents angle (degrees) and the vertical axis represents signal intensity (arbitrary unit). As is clear from this graph, the intensity peak of the Si substrate (111) surface was observed, but the other peaks were extremely small values. It will be understood that although a small peak of GaN (0002) is observed, the peaks of GaN (10-10), GaN (10-11), etc. are also turbulent and are not clean crystals. Further, even if a PL light emitting device was constructed using this GaN crystal, no light could be emitted. Further, FIG. 9 shows a SEM surface photograph taken at the stage of forming the GaN buffer layer. As is apparent from this photograph, a flat GaN buffer layer is not formed, and the silicon substrate is exposed over a wide range. It is extremely difficult to epitaxially grow a good quality GaN crystal on such a rough surface.

Chapter 3 Modifications In the example described above, H ₂ is used as the carrier gas for preheating the carbon susceptor 16, but other gases may be used. What is important in the present embodiment is that the carrier gas is replaced from H ₂ to N ₂ at the time of desorption of hydrogen atoms. As a result, even when the temperature is lowered, once desorbed hydrogen atoms do not bind to the surface of the silicon substrate again. Further, N ₂ may be used as a carrier gas from the beginning.

In the present embodiment, the carrier gas is replaced from H ₂ to N ₂ , but may be replaced with a gas other than N ₂ . It is important to use a gas other than hydrogen gas.

It is a SEM (scanning electron microscope) photograph which shows the mode of the silicon substrate surface at the time of providing a GaN buffer layer on a silicon substrate. It is explanatory drawing explaining the principle of this invention. It is a block diagram of the crystal growth apparatus used in this Embodiment. It is a graph showing the temperature change etc. in the case of crystal growth in this Embodiment. It is a measurement graph of the X-ray diffraction pattern of the GaN crystal created in this Embodiment. It is a graph which shows the light emission characteristic of the light emitting element produced using the GaN crystal produced in this Embodiment. It is a SEM photograph showing sectional drawing of the GaN crystal created in this embodiment. It is a measurement graph of the X-ray diffraction pattern of the GaN crystal created as a comparative example. It is a SEM photograph showing the surface of the GaN crystal created as a comparative example. 4 is a photograph showing the state of the “hole” described in Non-Patent Document 1. It is a conceptual diagram when GaN epitaxy is grown on an AlN buffer layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 GaN crystal growth apparatus 12 Quartz reaction tube 12b Ejection port 14 Substrate crystal 16 Carbon susceptor 18 RF coil 20 N ₂ source 22 H ₂ source 24 Flow control device 26 Valve 28 TMG source 30 NH ₃ source

Claims (1)

In a method for crystal growth of gallium nitride on a silicon substrate,
A hydrogen desorption step of desorbing hydrogen atoms on the silicon substrate;
After the hydrogen desorption step, using a carrier gas not containing hydrogen, a gallium nitride buffer layer forming step for forming a gallium nitride buffer layer on the silicon substrate;
A crystal growth step for crystal growth of gallium nitride on the gallium nitride buffer layer;
Only including,
The gallium nitride crystal growth method, wherein the hydrogen desorption step includes a step of heating the silicon substrate to a temperature of 700 ° C. or higher .