JP5358955B2 - Method for forming p-type gallium nitride based semiconductor region - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a p-type gallium nitride semiconductor region by an ion implantation method. <P>SOLUTION: In the method for forming a p-type gallium nitride semiconductor region, a gallium nitride semiconductor film 13 is ion-implanted with a p-type dopant 17 by using a mask 15 to form a gallium nitride semiconductor film 13b. After the mask 15 is removed, the gallium nitride semiconductor film 13 is thermally treated in an atmosphere 21 containing at least either ammonia or hydrazine compound, without the formation of a cap film, or the like, on the surface of a gallium nitride semiconductor film 13e, at a temperature T<SB>A</SB>, forming a p-type gallium nitride semiconductor region 13h. The surface of the gallium nitride semiconductor film 13e is exposed to the atmosphere 21. A gallium nitride semiconductor film 13g is formed by a thermal treatment. The gallium nitride semiconductor film 13g includes a region 13h, where the implanted ion is activated and a region 13d which is kept undoped. as it is. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a method for forming a p-type gallium nitride based semiconductor region.

Non-Patent Document 1 describes a method for manufacturing a p-type semiconductor in an ion implantation method. After co-implanting beryllium (Be) and oxygen (O) into the undoped GaN epitaxial layer on the sapphire substrate, annealing is performed in an atmosphere of nitrogen (N ₂ ). Thereafter, an electrode for hole measurement was produced. According to the results of hole measurement, p-type GaN was obtained by co-addition of beryllium (Be) and oxygen (O). The activation energy of the acceptor was 57 meV or less. After co-implanting magnesium (Mg) and oxygen (O) into an undoped GaN epitaxial layer on a sapphire substrate, annealing was performed in an atmosphere of nitrogen (N ₂ ), but no p-type characteristics were obtained. .

Non-Patent Document 2 describes a method of manufacturing a p-type GaN semiconductor by a thermal diffusion method. An Mg / Ni / Pt electrode was formed on the undoped GaN on the sapphire substrate by EB vapor deposition. Next, activation annealing was performed after thermal diffusion treatment in an ammonia (NH ₃ ) atmosphere. After annealing, an electrode for hole measurement was produced. According to the results of hole measurement, p-type GaN was obtained by diffusion of magnesium (Mg).
Journal of Applied Physics, vol. 90 (2001) 3750 The 68th Japan Society of Applied Physics Academic Lecture Proceedings 4p-N-5

In Non-Patent Document 1, a p-type semiconductor with good characteristics is obtained in GaN which is co-implanted with beryllium (Be) and oxygen (O) and N ₂ annealed, but magnesium (Mg) and oxygen (O) are obtained. In GaN that has been co-implanted with N _{2 and} annealed with N ₂ , no p-type semiconductor is obtained. In Non-Patent Document 2, p-type GaN is obtained by adding Mg by a thermal diffusion method instead of an ion implantation method. However, in the thermal diffusion method, it is difficult to control the profile of the p-type dopant. In addition, it is difficult to control the low p-type dopant concentration. Furthermore, it is difficult to form a fine p-type semiconductor region.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a method of forming a p-type gallium nitride semiconductor region by an ion implantation method.

  One aspect of the present invention relates to a method of forming a p-type gallium nitride based semiconductor region. This method includes (a) a step of ion-implanting a p-type dopant into a gallium nitride semiconductor, and (b) heat-treating the gallium nitride semiconductor in a first atmosphere of a gas containing nitrogen after the ion implantation. And a step of forming a p-type gallium nitride based semiconductor region. The first atmosphere includes at least one of ammonia and a hydrazine compound.

  According to this method, after the ion implantation, the ion-implanted gallium nitride semiconductor is heat-treated in an atmosphere containing at least one of ammonia and a hydrazine compound, so atoms near the surface of the gallium nitride semiconductor can be obtained. As a result of the rearrangement due to the migration, the crystallinity of the gallium nitride semiconductor is restored, and the p-type dopant implanted into the gallium nitride semiconductor enters an appropriate site in the gallium nitride semiconductor.

  The method according to the present invention may further comprise a step of depositing the gallium nitride based semiconductor prior to the ion implantation. At least a portion of the gallium nitride based semiconductor is an undoped region, and the ion implantation is performed in the undoped region. In this method, a p-type semiconductor region can be formed in part or all of the undoped gallium nitride semiconductor. Alternatively, the gallium nitride based semiconductor may be a bulk crystal such as a gallium nitride based semiconductor wafer.

  In the method according to the present invention, the p-type dopant may include at least one of magnesium and beryllium. According to this method, a p-type gallium nitride based semiconductor containing at least one of magnesium and beryllium can be formed. The p-type dopant may be magnesium. Alternatively, the p-type dopant may be beryllium.

  The method according to the present invention may further include a step of raising the temperature to the temperature of the heat treatment in a second atmosphere before forming the p-type gallium nitride based semiconductor region. The second atmosphere may include at least one of ammonia and a hydrazine compound.

  The method according to the present invention can further include a step of lowering the temperature of the heat treatment in a third atmosphere of a gas containing nitrogen after forming the p-type gallium nitride based semiconductor region. The third atmosphere may include at least one of ammonia and a hydrazine compound.

  The method according to the present invention may further include a step of implanting oxygen ions into the gallium nitride based semiconductor prior to the heat treatment. The gallium nitride based semiconductor may have a portion into which both the oxygen and the p-type dopant are ion-implanted, and the p-type dopant may include beryllium or magnesium. According to this method, a gallium nitride based semiconductor region exhibiting good p-type characteristics can be formed by co-addition of oxygen and beryllium.

  In the method according to the present invention, the gallium nitride based semiconductor may include at least one of GaN, InGaN, AlGaN, and InAlGaN.

  In the method according to the present invention, the ion implantation is performed on GaN of the gallium nitride semiconductor, and the temperature of the heat treatment is preferably 800 degrees Celsius or higher. Moreover, it is preferable that the temperature of the said heat processing is 1200 degrees C or less. According to this method, p-type GaN is formed.

  In the method according to the present invention, the ion implantation is performed on the GaN-based semiconductor InGaN, and the temperature of the heat treatment is preferably 900 degrees Celsius or less. Moreover, it is preferable that the temperature of the said heat processing is 600 degreeC or more. According to this method, p-type InGaN is formed.

  In the method according to the present invention, the ion implantation is performed on AlGaN of the gallium nitride semiconductor, and the temperature of the heat treatment is preferably 800 degrees Celsius or higher. The temperature of the heat treatment is preferably 1300 degrees Celsius or less. According to this method, p-type AlGaN is formed.

  In the method according to the present invention, it is preferable that the atmosphere does not contain a hydrazine compound and contains ammonia. Ammonia can prevent the escape of nitrogen from the GaN-based semiconductor surface and promote surface migration.

  The above and other objects, features, and advantages of the present invention will become more readily apparent from the following detailed description of preferred embodiments of the present invention, which proceeds with reference to the accompanying drawings.

  As described above, according to the present invention, a method for forming a p-type gallium nitride based semiconductor region by an ion implantation method is provided.

  The knowledge of the present invention can be easily understood by considering the following detailed description with reference to the accompanying drawings shown as examples. Subsequently, an embodiment according to a method of forming a p-type gallium nitride based semiconductor region of the present invention will be described with reference to the accompanying drawings. Where possible, the same parts are denoted by the same reference numerals.

  1 to 3 are drawings showing main steps in a method of forming a p-type gallium nitride based semiconductor region according to the present embodiment. A substrate 11 is prepared. It is used for depositing a gallium nitride based semiconductor on the substrate 11. As the substrate 11, for example, a Si, SiC, ZnO, sapphire substrate, a group III nitride substrate, or the like can be used. As the group III nitride substrate, for example, an AlN substrate or a substrate made of a gallium nitride material can be used. As the gallium nitride-based material for the substrate, GaN, AlGaN, InGaN, or the like can be used. If necessary, ion implantation can be performed without growing a gallium nitride based semiconductor film on a substrate made of a gallium nitride based material or prior to growing a gallium nitride based semiconductor film.

  The substrate 11 is placed on the apparatus 10a. The apparatus 10a is a crystal growth apparatus. As shown in FIG. 1A, a gallium nitride based semiconductor film 13 is deposited on the main surface 11 a of the substrate 11. Epitaxial growth is performed, for example, by metal organic vapor phase epitaxy, HVPE, MBE, or the like. In the present embodiment, the gallium nitride based semiconductor film 13 can be undoped, for example, but is not limited thereto. The gallium nitride based semiconductor film 13 may be an n-type semiconductor layer doped with Si. The gallium nitride based semiconductor film 13 can include at least one region of GaN, InGaN, AlGaN, and InAlGaN, for example. If necessary, in addition to the gallium nitride based semiconductor film 13, a film forming configuration can be further provided.

  The film formation temperature of GaN can be, for example, 800 degrees Celsius or higher. The film formation temperature of GaN can be, for example, 1200 degrees Celsius or less. The deposition temperature of InGaN can be, for example, 600 degrees Celsius or higher. The InGaN film formation temperature can be, for example, 900 degrees Celsius or less. The deposition temperature of AlGaN can be, for example, 1000 degrees Celsius or higher. Further, the deposition temperature of AlGaN can be, for example, 1300 degrees Celsius or less. The deposition temperature of InAlGaN can be, for example, 600 degrees Celsius or more. In addition, the deposition temperature of InAlGaN can be, for example, 900 degrees Celsius or less.

  As shown in FIG. 1B, a mask 15 is formed on the main surface 13a of the gallium nitride based semiconductor film 13 if necessary. The mask 15 has an opening on a region where a p-type dopant is to be implanted by ion implantation. When ion implantation is performed on the entire surface 13a of the gallium nitride based semiconductor film 13, the mask 15 is not formed.

  After forming the mask 15, the gallium nitride based semiconductor film 13 and the substrate 11 are placed in the ion implantation apparatus 10b. As shown in FIG. 2A, ion implantation of a p-type dopant 17 is performed on the gallium nitride based semiconductor film 13 using a mask 15 to form a gallium nitride based semiconductor film 13b. The p-type dopant can include at least one of magnesium and beryllium. The p-type dopant may be magnesium, or the p-type dopant may be beryllium. The gallium nitride based semiconductor film 13 is damaged by ion implantation. Further, the implanted p-type dopant has not yet been activated. After the ion implantation, a gallium nitride based semiconductor film 13b having a region containing at least one of magnesium and beryllium can be formed. The gallium nitride based semiconductor film 13b includes a region 13c containing a p-type dopant that is not activated and a region 13d that is not ion-implanted (remains undoped).

  If necessary, another dopant 19 is ion-implanted into the gallium nitride based semiconductor film 13b using the mask 15 to form a gallium nitride based semiconductor film 13e as shown in FIG. Another dopant 19 can be a p-type dopant.

  In one embodiment, prior to the heat treatment, another dopant 19 can be ion-implanted into the gallium nitride based semiconductor film 13b. The dopant 19 can be, for example, an n-type dopant oxygen. In one example, the gallium nitride based semiconductor film 13e includes a region 13f in which both oxygen and the p-type dopant 17 are ion-implanted, and a region 13d in which ions are not implanted (remains undoped). Preferably, co-addition of oxygen and beryllium is preferred. By co-addition of oxygen and beryllium, a gallium nitride based semiconductor region exhibiting good p-type characteristics can be formed. Alternatively, co-addition of oxygen and magnesium is preferable. By co-addition of oxygen and magnesium, a gallium nitride based semiconductor region exhibiting good p-type characteristics can be formed. The dose of oxygen 19 is preferably larger than the dose of p-type dopant 17. A preferable range of the dose ratio is (oxygen dose / p-type dopant dose) = 1 or more, and preferably 4 or less.

After the ion implantation, the mask 15 is removed as shown in FIG. After removing the mask 15, the gallium nitride based semiconductor film 13b and the substrate 11 are placed in the heat treatment apparatus 10c. Although it is preferable that there is no cap film or the like on the surface of the gallium nitride based semiconductor film 13e, the effect becomes weak even after the formation of a cap layer or the like covering the surface of the gallium nitride based semiconductor film 13e. The heat treatment is effective. First, raising the temperature of the heat treatment apparatus 10c to a temperature T _A for the heat treatment. Subsequently, as shown in FIG. 3 (b), a heat treatment to the p-type gallium nitride based semiconductor region 13h at a temperature T _A of the first gallium nitride in an atmosphere 21 of the semiconductor film 13 of the gas containing nitrogen is formed To do. The first atmosphere 21 can include at least one of ammonia and a hydrazine compound. The surface of the gallium nitride based semiconductor film 13e is exposed to the atmosphere 21. As the hydrazine compound, a gas containing a nitrogen radical such as di-methyl-hydrazine or the like can be used. A gallium nitride based semiconductor film 13g is formed by the heat treatment. The gallium nitride based semiconductor film 13g includes a region 13h in which implanted ions are activated and a region 13d that remains undoped. The region 13 h in which the implanted ions are activated and the region 13 d that remains undoped form a junction 23. When the conductivity type of the region 13h is different from the conductivity type of the region 13d, the junction 23 is a pn junction. When the conductivity type of the region 13h is the same as the conductivity type of the region 13d, the junction 23 is a pp junction or an nn junction. After heat treatment, the temperature is decreased the temperature of the heat treatment apparatus 10c from the temperature T _A for the heat treatment.

The temperature increase in the heat treatment apparatus 10c can be performed in a second atmosphere of a gas containing nitrogen. The second atmosphere can contain at least one of ammonia and a hydrazine-based compound. This is because there is an effect of preventing nitrogen depletion and surface roughness when the temperature is raised, and the second atmosphere is effective in a temperature region above the temperature at which nitrogen depletion and surface roughness may occur. To lowering the temperature of the heat treatment apparatus 10c from the temperature T _A for the heat treatment. The temperature drop in the heat treatment apparatus 10c can be performed in a third atmosphere of a gas containing nitrogen. The third atmosphere can contain at least one of ammonia and a hydrazine-based compound. This is because there is an effect of preventing nitrogen depletion and surface roughness when the temperature is high, and the third atmosphere is effective in a temperature region that is higher than the temperature at which nitrogen depletion and surface roughness may occur.

  By these steps, a p-type semiconductor region can be formed in part or all of the undoped gallium nitride semiconductor. As already described, ion implantation can be performed on a bulk crystal such as a gallium nitride based semiconductor wafer.

  According to this method, after ion implantation, the gallium nitride semiconductor containing implanted ions is heat-treated in an atmosphere containing at least one of ammonia and a hydrazine compound, so atoms near the surface of the gallium nitride semiconductor can be obtained. The rearrangement is caused by the migration, and the crystallinity of the gallium nitride semiconductor is restored, and the p-type dopant implanted into the gallium nitride semiconductor enters an appropriate site in the gallium nitride semiconductor.

When the ion implantation of p-type dopant is performed in the GaN region of the gallium nitride based semiconductor, the temperature T _A of the heat treatment is preferably at least 800 degrees Celsius. This is because a sufficient activation effect cannot be obtained at a temperature lower than this temperature. Further, it is preferable that the temperature _{T A} is less than 1200 degrees Celsius. This is because it is difficult to obtain p-type carriers due to surface roughness, crystallinity degradation, and the like. According to this method, p-type GaN is formed.

When the ion implantation is performed in the InGaN region of the gallium nitride based semiconductor, the temperature T _A of the heat treatment is preferably not more than 900 degrees Celsius. This is because it becomes difficult to obtain p-type carriers due to surface roughness, deterioration of crystallinity, and the like. Further, it is preferable that the temperature _{T A} is over 600 degrees Celsius. The sufficient activation effect at a temperature below the temperature because not give al. According to this method, p-type InGaN is formed.

When the ion implantation is performed in the AlGaN region of the gallium nitride based semiconductor, the temperature T _A of the heat treatment is preferably at least 800 degrees Celsius. This is because a sufficient activation effect cannot be obtained at a temperature lower than this temperature. Further, it is preferable that the temperature _{T A} is less than 1300 degrees Celsius. This is because it becomes difficult to obtain p-type carriers due to surface roughness, deterioration of crystallinity, and the like. According to this method, p-type AlGaN is formed.

When the ion implantation is performed in the InAlGaN region of the gallium nitride based semiconductor, the temperature T _A of the heat treatment is preferably at least 600 degrees Celsius. This is because it is difficult to obtain p-type carriers due to surface roughness, crystallinity degradation, and the like. Further, it is preferable that the temperature _{T A} is less than 900 degrees Celsius. This is because it becomes difficult to obtain p-type carriers due to surface roughness, deterioration of crystallinity, and the like. According to this method, p-type InAlGaN is formed.

  According to the experiments by the inventors, it is preferable that the heat treatment temperature of GaN and InGaN is substantially in the same range as the growth temperature. For example, if the preferable film formation temperature range of GaN is 800 degrees Celsius or more and 1200 degrees Celsius or less, the heat treatment temperature range for activation and annealing is preferably 800 degrees Celsius or more and 1200 degrees Celsius or less. The preferred heat treatment temperature for InGaN decreases with increasing indium composition. In the range of 5% to 30% (for example, 20%) of the indium composition, the heat treatment temperature is preferably 700 ° C. or more and 800 ° C. or less as described above, for example.

  Further, according to experiments by the inventors, it is preferable that the heat treatment temperature of AlGaN is approximately the same as the growth temperature or a temperature equal to or higher than the film formation temperature. The preferred heat treatment temperature for AlGaN increases with increasing aluminum composition. In the aluminum composition range of 20% to 30% (for example, 25%), the heat treatment temperature is preferably, for example, 1000 degrees Celsius or more and 1100 degrees Celsius or less as described above. In the aluminum composition range of 40% to 60% (eg, 50%), the heat treatment temperature is preferably 1100 degrees Celsius or more and 1200 degrees Celsius or less as described above, for example.

(Example)
An epitaxial substrate was produced by growing an undoped GaN epitaxial film on the sapphire substrate. The thickness of the undoped GaN epitaxial film is 2 μm.
Ion implantation was performed on the epitaxial substrate under the following four conditions (A1, A2, B1, B2).
A1: Ion implantation with only Mg ions.
The implantation conditions were such that the total dose of Mg was 1.7 × 10 ¹⁵ cm ⁻² and the Mg concentration up to a depth of 0 μm to 0.3 μm was about 5 × 10 ¹⁹ cm ⁻³ .
A2: Co-injection of Mg and oxygen.
The total dose of Mg is 1.7 × 10 ¹⁵ cm ⁻² . Implantation conditions were used such that the Mg concentration up to a depth of 0 μm to 0.3 μm was about 5 × 10 ¹⁹ cm ⁻³ .
Oxygen (O) was used under such implantation conditions that the dose of twice the Mg dose and the O concentration up to a depth of 0 μm to 0.3 μm were substantially constant.
B1: Ion implantation using only Be ions.
The implantation conditions were such that the total dose of Be was 1.7 × 10 ¹⁵ cm ⁻² and the Mg concentration up to a depth of 0 μm to 0.3 μm was about 5 × 10 ¹⁹ cm ⁻³ .
B2: Co-implantation of Be and oxygen.
The implantation conditions were such that the total dose of Be was 1.7 × 10 ¹⁵ cm ⁻² and the Mg concentration up to a depth of 0 μm to 0.3 μm was about 5 × 10 ¹⁹ cm ⁻³ .
For the oxygen (O), implantation conditions were used such that the dose amount twice the Be dose amount and the O concentration up to a depth of 0 μm to 0.3 μm were substantially constant.

After the ion implantation, annealing was performed at 1050 degrees Celsius for about 1 minute using a crystal growth apparatus as a heat treatment apparatus. The heat treatment atmosphere was N ₂ or NH ₃ . Thereafter, an ohmic electrode (Ni) was formed on the ion-implanted GaN region. A list of the results of Hall measurement is shown in FIG. FIG. 4 is a drawing showing a list of carrier polarities and carrier concentrations obtained from the hole measurement results for each condition. The heat treatment atmosphere during the increase of the annealing temperature was ammonia and nitrogen. The heat treatment atmosphere during the drop from the annealing temperature was ammonia and nitrogen.

By annealing in an ammonia atmosphere, a p-type gallium nitride region was obtained on an epitaxial substrate under all conditions. Also, the hole concentration can be increased by annealing in an ammonia atmosphere as compared to annealing in an N ₂ atmosphere as in condition B2. Therefore, good activation is possible in an ammonia atmosphere. Further, a p-type semiconductor was obtained only by annealing in an N ₂ atmosphere as in condition B2.

  By annealing in an ammonia atmosphere, atoms near the surface of the GaN epitaxial layer undergo migration, and the crystallinity is restored. At the same time, implanted Mg, Be, etc. can enter appropriate sites in the crystal lattice. it is conceivable that. A gas containing a nitrogen radical, for example, a hydrazine compound such as di-methyl-hydrazine or the like may be used instead of or together with ammonia. Thereby, nitrogen escape from the gallium nitride based semiconductor surface can be prevented, and an atmosphere capable of promoting surface migration can be used for heat treatment.

Referring to FIG. 4, under conditions A1, A2, and B1, an n-type GaN semiconductor is obtained by heat treatment in an N ₂ atmosphere, while a p-type GaN semiconductor is obtained by heat treatment in an NH ₃ atmosphere. There is also. When this heat treatment was applied to Si ion implantation, there were effects such as an increase in carrier concentration.

  While the principles of the invention have been illustrated and described in the preferred embodiments, it will be appreciated by those skilled in the art that the invention can be modified in arrangement and detail without departing from such principles. The present invention is not limited to the specific configuration disclosed in the present embodiment. We therefore claim all modifications and changes that come within the scope and spirit of the following claims.

FIG. 1 is a drawing showing main steps in a method for forming a p-type gallium nitride based semiconductor region according to the present embodiment. FIG. 2 is a drawing showing main steps in the method of forming a p-type gallium nitride based semiconductor region according to the present embodiment. FIG. 3 is a drawing showing major steps in the method of forming the p-type gallium nitride based semiconductor region according to the present embodiment. FIG. 4 is a drawing showing a list of carrier polarities and carrier concentrations obtained from the hole measurement results for each condition.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10a ... Crystal growth apparatus, 11 ... Substrate, 11a ... Substrate main surface, 13 ... Gallium nitride semiconductor film, 13a ... Gallium nitride semiconductor main surface, 13b ... Gallium nitride semiconductor film after ion implantation, 13c ... Active A region containing a p-type dopant that is not formed, 13d... A region where ions are not implanted, 13e. , 13 g ... gallium nitride based semiconductor film, 15 ... mask, 17 ... p-type dopant, 19 ... another dopant, 21 ... first atmosphere

Claims (9)

A method of forming a p-type gallium nitride based semiconductor region,
Performing ion implantation of a p-type dopant into a gallium nitride semiconductor;
Performing ion implantation of oxygen into the gallium nitride based semiconductor;
Forming a p-type gallium nitride based semiconductor region by heat-treating the gallium nitride based semiconductor in a first atmosphere of a nitrogen-containing gas after ion implantation of the co-addition of the p-type dopant and the oxygen;
With
The gallium nitride based semiconductor has a portion in which both the oxygen and the p-type dopant are ion-implanted,
The p-type dopant includes beryllium or magnesium,
(The dose amount of the oxygen / the dose amount of the p-type dopant) is 2 or more and 4 or less,
The method according to claim 1, wherein the first atmosphere includes at least one of ammonia and a hydrazine compound. The method according to claim 1 , wherein the gallium nitride based semiconductor includes at least one of GaN, InGaN, AlGaN, and InAlGaN. Prior to the ion implantation, the method further comprises the step of depositing the gallium nitride based semiconductor, wherein at least a part of the gallium nitride based semiconductor is an undoped region, and the ion implantation is performed in the undoped region. The method according to claim 1 or claim 2 . Before forming the p-type gallium nitride based semiconductor region, further comprising a step of raising the temperature to a temperature of the heat treatment in a second atmosphere;
The method according to any one of claims 1 to 3 , wherein the second atmosphere includes at least one of ammonia and a hydrazine-based compound. After forming the p-type gallium nitride based semiconductor region, further comprising the step of lowering the temperature of the heat treatment at a third atmosphere gas containing nitrogen, any one of claims 1 to 4, characterized in that The method according to one item. The ion implantation is performed on GaN of the gallium nitride semiconductor,
The temperature of the heat treatment is 800 degrees Celsius or higher,
The method according to claim 2 , wherein the temperature of the heat treatment is 1200 degrees Celsius or less. The ion implantation is performed on the GaN-based semiconductor InGaN,
The method according to claim 2 , wherein the temperature of the heat treatment is 900 degrees Celsius or less. The ion implantation is performed on the GaN-based semiconductor AlGaN,
The method according to claim 2 , wherein the temperature of the heat treatment is 800 degrees Celsius or more. The method according to any one of claims 1 to 8 , wherein the atmosphere does not contain a hydrazine compound and contains ammonia.

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