JP2008192677A - METHOD OF IMPROVING P-TYPE CONDUCTIVITY OF Mg-DOPED GROUP III NITRIDE SEMICONDUCTOR AND MANUFACTURING METHOD OF P-TYPE GROUP III NITRIDE SEMICONDUCTOR - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of obtaining an Al-rich group III nitride semiconductor having excellent P-type conductivity. <P>SOLUTION: A crystal layer made of Mg-doped Al<SB>x</SB>In<SB>y</SB>Ga<SB>1-x-y</SB>N (0≤x≤1, 0≤y≤1, 0≤x+y≤1) is subjected to first processing, i.e., the thermal processing of holding the crystal layer for 20 minutes or more at a first holding temperature within a range of 700-850°C in an atmosphere not containing hydrogen, preferably in a nitrogen atmosphere, and then the second processing, i.e., the thermal processing of holding it for only a short time of two minutes or less at a second thermal processing temperature of a range of 900-1,000°C in an atmosphere not including hydrogen. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technology for obtaining a group III nitride semiconductor having good P-type conductivity, particularly a group III nitride semiconductor having a large Al composition ratio.

  Group III nitride semiconductors such as GaN are used in various devices including optical devices such as light emitting devices and light receiving devices. These devices are generally formed by laminating a crystal layer made of a group III nitride semiconductor on a predetermined substrate by an epitaxial growth method. And a low-resistance crystal layer imparted with P-type or N-type conductivity by doping.

  In order to make a group III nitride semiconductor such as GaN P-type, it is common to dope Mg as an acceptor during crystal growth. However, in the case where a semiconductor layer made of P-GaN is formed by an epitaxial growth method such as MOCVD, hydrogen derived from ammonia serving as a nitrogen source is mixed during growth, so that Mg is inactivated by hydrogen. Therefore, the obtained semiconductor layer remains high resistance. Therefore, it is common to perform a treatment (so-called activation treatment) that promotes ionization of Mg by desorbing hydrogen by performing a heat treatment in an atmosphere that does not contain hydrogen after growth (for example, Patent Documents). 1). In addition to these methods, it is also known that ionization of Mg can be promoted by electron beam irradiation (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 05-183189 Japanese Patent Laid-Open No. 03-218625

  The methods disclosed in Patent Document 1 and Patent Document 2 convert a group III nitride mixed crystal semiconductor containing not only Ga but also Al or In as a group III element and doped with Mg to act as an acceptor into a p-type. Even in this case, the same applies. However, a group III nitride semiconductor in which the composition ratio of Al is relatively larger than the composition ratio of other group III elements has a larger band gap than other group III nitride semiconductors that do not, and Mg When the activation treatment as disclosed in Patent Document 1 is performed on a group III nitride semiconductor having a relatively high Al composition ratio, since the activation energy for activating is large, It is believed that heat treatment needs to be performed at a higher temperature.

  However, when heat treatment is performed at a high temperature on a group III nitride semiconductor having a large Al composition ratio, oxygen is likely to be mixed, and nitrogen depletion occurs near the surface, resulting in a deviation from the stoichiometric composition. Oxygen or nitrogen vacancies introduced thereby act as donors in the group III nitride semiconductor, so that the effect of Mg as an acceptor obtained by heat treatment is compensated, and sufficient P-type is realized. There is a problem that it is not.

  The present invention has been made in view of the above problems, and provides a method for obtaining a group III nitride semiconductor having good P-type conductivity, particularly a group III nitride semiconductor having a large Al composition ratio. The purpose is to provide.

In order to solve the above problems, the invention of claim 1 is a group III of Mg _x doped Al _x In _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). A method for improving P-type conductivity in a nitride semiconductor, wherein the group III nitride semiconductor is held at a first holding temperature belonging to a temperature range of 700 ° C. to 850 ° C. in an atmosphere not containing hydrogen. Performing a heat treatment step and a second heat treatment step of holding the group III nitride semiconductor that has undergone the first heat treatment step at a second holding temperature belonging to a temperature range of 900 ° C. to 1000 ° C. for a short time of 2 minutes or less. It is characterized by.

The invention of claim 2 is the method for improving the P-type conductivity of the Mg-doped group III nitride semiconductor according to claim 1, wherein the group III nitride semiconductor is Al _x In _y Ga _1-xy N (0. 4 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1).

  The invention of claim 3 is the method for improving the P-type conductivity of the Mg-doped group III nitride semiconductor according to claim 1 or 2, wherein the second holding temperature is 950 ° C. To do.

  The invention of claim 4 is the method for improving the P-type conductivity of the Mg-doped group III nitride semiconductor according to any one of claims 1 to 3, wherein the first holding temperature in the first heat treatment step. The holding time at is set to 20 minutes or more.

  The invention of claim 5 is the method for improving the P-type conductivity of the Mg-doped group III nitride semiconductor according to any one of claims 1 to 4, wherein the first holding temperature in the first heat treatment step. Is set to 800 ° C.

  A sixth aspect of the invention is a method for improving the P-type conductivity of an Mg-doped group III nitride semiconductor according to any one of the first to fifth aspects, wherein the Mg-doped group III nitride semiconductor is epitaxially formed on a predetermined underlayer. The first heat treatment step and the second heat treatment step are performed by heating the semiconductor layer made of the group III nitride semiconductor.

  The invention of claim 7 is the method for improving the P-type conductivity of the Mg-doped group III nitride semiconductor according to claim 6, wherein an AlN epitaxial film is formed on the sapphire single crystal substrate as the underlayer. A template substrate is used.

The invention of claim 8 is a method for producing a P-type group III nitride semiconductor comprising Al _x In _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). A growth step of epitaxially growing the semiconductor layer made of the group III nitride semiconductor by MOCVD while doping Mg on a predetermined underlayer, and an atmosphere containing no hydrogen in the semiconductor layer obtained by the growth step A first heat treatment step for holding at a first holding temperature belonging to a temperature range of 700 ° C. to 850 ° C., and the semiconductor layer that has undergone the first heat treatment step at 900 ° C. to 1000 ° C. in an atmosphere that does not contain hydrogen. And a second heat treatment step of holding at a second holding temperature belonging to the temperature range for a short time of 2 minutes or less.

The invention of claim 9 is the method for producing a P-type group III nitride semiconductor according to claim 8, wherein the group III nitride semiconductor is Al _x In _y Ga _1-xy N (0.4 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1).

  A tenth aspect of the invention is a method for producing a P-type group III nitride semiconductor according to the eighth or ninth aspect, wherein the second holding temperature is 950 ° C.

  An eleventh aspect of the invention is a method for producing a P-type group III nitride semiconductor according to any one of the eighth to tenth aspects, wherein the holding time at the first holding temperature in the first heat treatment step. Is 20 minutes or more.

  The invention of claim 12 is the method for producing a P-type group III nitride semiconductor according to any one of claims 8 to 11, wherein the first holding temperature in the first heat treatment step is 800 ° C. It is characterized by.

  A thirteenth aspect of the invention is a method for producing a P-type group III nitride semiconductor according to any one of the eighth to twelfth aspects, wherein an AlN epitaxial film is formed on the sapphire single crystal substrate as the underlayer. A template substrate on which is formed is used.

  According to the first to thirteenth inventions, for example, a group III nitride semiconductor having an excellent P-type conductivity having a specific resistance of about 1 Ωcm or less can be obtained regardless of the Al composition ratio.

  In particular, according to the invention of claim 2 and claim 9, a group III nitride semiconductor P-type conductor having a large Al composition ratio can be obtained.

In the method according to the present embodiment, Al _x In _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) doped with Mg for the purpose of acting as an acceptor element. ) In which a group III nitride semiconductor exhibits P-type conductivity, in other words, Al _x In _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) And a P-type group III nitride semiconductor in which Mg acts as an acceptor element.

<Applicable target>
The method according to the present embodiment is applied to Al _x In _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) doped with Mg for the purpose of acting as an acceptor element. , 0 ≦ x + y ≦ 1). The group III nitride semiconductor is handled in the form of a crystal layer (semiconductor layer) formed on a base substrate (base layer) such as a C-plane sapphire single crystal substrate using a known epitaxial growth method such as MOCVD. There are many cases. This embodiment will also be described for this case. However, the aspect accompanied by the base substrate is not essential, and the same effect can be obtained even when the method according to the present embodiment is provided in an aspect not having this.

  As a base substrate, in addition to the above-described embodiment in which the C-plane sapphire single crystal substrate is directly used, a so-called template substrate (epitaxial substrate) in which an AlN layer is epitaxially grown on the single crystal substrate using MOCVD. May be used. For example, it is a preferable example to use a base substrate in which an AlN layer having a thickness of about several μm is formed by MOCVD on a C-plane sapphire single crystal substrate having a thickness of about several hundred μm. In this case, a crystal layer made of a group III nitride semiconductor can be formed with good crystal quality.

A crystal layer made of Al _x In _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) can be obtained by using various methods depending on the device to be manufactured. May be formed. Further, if the Mg concentration in the crystal layer is on the order of about 10 ²⁰ / cm ³ , it is sufficient to ensure good conductivity.

If the crystal layer is epitaxially grown by MOCVD, Mg is doped with CP ₂ Mg (cyclopentadienylmagnesium: Mg (C ₅ H ₅ ) ₂ ) gas and TMA (trimethylaluminum; Al (CH ₃ ) ₃ ), TMG (trimethylgallium; Ga (CH ₃ ) ₃ ), TMI (trimethylindium; In (CH ₃ ) ₃ ) and other group III metal source gases, nitrogen source gases such as NH _3, etc. This is realized by supplying at a flow rate of. Even when a group III nitride semiconductor is obtained by another known method, it can be realized by appropriately applying a known doping method according to each method.

Further, regarding a laminate including a plurality of crystal layers made of Al _x In _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) having the same or different composition, If Mg is doped in each of several layers, it is also possible to develop P-type conductivity by applying these methods to the method according to the present embodiment all at once. It is.

<Treatment for obtaining P-type conductivity>
Also in the present embodiment, Mg is activated by heat treatment for heating a group III nitride semiconductor doped with Mg to obtain P-type conductivity. It is the same. However, the method according to the present embodiment is characterized in that after performing the conventional heat treatment as the first heat treatment, the heat treatment at a higher temperature is performed as the second heat treatment for a short time.

First, in the first heat treatment, a crystal made of Al _x In _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) doped with Mg as described above is processed. A layer formed on a predetermined base substrate is prepared, and this is placed in a predetermined heat treatment furnace in which an atmosphere containing at least hydrogen is formed, preferably a nitrogen atmosphere is formed. Heat holding is performed at an arbitrary holding temperature in a range of ˜850 ° C. (also referred to as a first holding temperature or a first heat treatment temperature), preferably at 800 ° C. for a time of 20 minutes or longer (also referred to as a first holding time). . Note that the hydrogen-free atmosphere is realized because Mg activation is realized by desorbing hydrogen bonded to Mg in the crystal layer. This is to promote such desorption by reducing as much as possible.

  This first heat treatment is the same as the treatment performed as a conventional method as described above, but if the Al composition ratio in the crystal layer is small, it alone is effective to some extent for the activation of Mg. The inventors of the present invention have confirmed that Mg cannot always be sufficiently activated when the composition of the layer is Al-rich.

For example, FIG. 1 shows that the first heat treatment is performed for 20 minutes at a first holding temperature of 800 ° C. for a crystal layer represented by Al _x Ga _1-x N (0 ≦ x ≦ 1), and the second heat treatment is performed. It is a figure which shows the specific resistance before and after each heat processing when performing this for 1 minute with a holding temperature of 950 degreeC. From FIG. 1, in the range of x ≧ 0.4 where the Al composition ratio is relatively large, the specific resistance after the first heat treatment is about 20 Ωcm or more. It can be seen that has not decreased.

  In the present embodiment, an atmosphere containing at least hydrogen, preferably a nitrogen atmosphere, is formed as the second heat treatment for the crystal layer after the first heat treatment (also with the base substrate). It is placed in a predetermined heat treatment furnace, and at an arbitrary holding temperature in the range of 900 ° C. to 1000 ° C. (also referred to as a second holding temperature or a second heat treatment temperature), preferably at 950 ° C. for a short time of 2 minutes or less. Heating and holding is performed only (also referred to as second holding time).

  By performing such second heat treatment, Mg is sufficiently activated even in the range of x ≧ 0.4 where sufficient conductivity was not obtained after the first heat treatment, and good P-type conductivity is obtained. It has not been known so far, and is the first finding found by the inventors of the present invention.

For example, in the case of Al _x Ga _1-x N (0 ≦ x ≦ 1) shown in FIG. 1, after the second heat treatment, the specific resistance is sufficiently reduced to 1 Ωcm or less even in the composition range of x ≧ 0.4. You can see that That is, in the composition range of x ≧ 0.4, sufficient P-type conductivity due to Mg activation cannot be obtained only by performing the first heat treatment corresponding to the conventionally known heat treatment. Good P-type conductivity can be obtained only by performing the second heat treatment. In addition, it can be seen that the specific resistance is further reduced by the second heat treatment even in the case of a composition that has already been achieved at about 1 Ωcm or less after the first heat treatment. In other words, the P-type conductivity can be further improved by performing the second heat treatment after the first heat treatment.

On the other hand, FIG. 2 shows the specific resistance values after the first heat treatment with the first holding temperature set to 800 ° C. and the holding time varied for the crystal layer composition Al _0.5 Ga _0.5 N. It is a figure which shows a change. FIG. 2 shows that even if the first heat treatment is performed for a long time, the specific resistance cannot be reduced as it is when the second heat treatment is performed. This is because if the holding time in the first heat treatment is lengthened, the same effect as in the second heat treatment cannot be obtained, and in particular, the second heat treatment is essential for reducing the specific resistance in the Al-rich crystal layer. It is understood that it means. 2 that the effect is small even if the first heat treatment is performed for 20 minutes or longer. It has been confirmed by the inventors of the present invention that these tendencies are the same for other composition ranges.

  That is, from FIG. 1 and FIG. 2, by performing a two-step heat treatment in which the second heat treatment is performed after performing the first heat treatment similar to the conventional method, regardless of the Al composition ratio (in the case of Al-rich). It is confirmed that good P-type conductivity in which Mg is sufficiently activated can be obtained. That is, it is confirmed that the P-type conductivity is improved.

  Next, the condition range in which good P-type conductivity can be obtained by such a two-step heat treatment will be further considered.

FIG. 3 shows the specific resistance when the first heat treatment is performed at 800 ° C. for 20 minutes and the second heat treatment is performed under different holding temperature conditions for the crystal layer composition Al _0.5 Ga _0.5 N. FIG. The holding time is 1 minute in all cases. From FIG. 3, it can be seen that the specific resistances at 900 ° C., 950 ° C., and 1000 ° C. are significantly smaller than when the second heat treatment temperature is 875 ° C. and 1025 ° C. It is confirmed by the inventor of the present invention that this tendency is the same for the other composition ranges, and is particularly remarkable in the range of x ≧ 0.4.

Similarly, FIG. 4 shows that when the composition of the crystal layer is Al _0.5 Ga _0.5 N, after the first heat treatment is performed at 800 ° C. for 20 minutes, the second holding temperature is set at 950 ° C. It is a figure about the specific resistance at the time of performing 2nd heat processing by holding time. Note that the second heat treatment time of 0 means that only the first heat treatment is performed and the second heat treatment is not performed. From FIG. 4, when the second heat treatment is performed for a short time of 2 minutes or less, the specific resistance is remarkably reduced and the heat treatment effect can be obtained satisfactorily. I understand that it is small. It has been confirmed by the inventors of the present invention that this tendency is the same for other composition ranges. Although illustration is omitted, it is confirmed by the inventor of the present invention that this tendency is the same for other composition ranges, and is particularly remarkable in the range of x ≧ 0.4.

  That is, from the results of FIGS. 3 and 4, it is confirmed that the second heat treatment has a suitable condition range. Specifically, it is confirmed that the second holding temperature is preferably between 900 ° C. and 1000 ° C. and the holding time is 2 minutes or less. This result shows that when a group III nitride semiconductor having an Al-rich composition range is heated to a temperature higher than 1000 ° C. or longer than 2 minutes, oxygen contamination and nitrogen depletion are remarkably caused. It is considered that the effect of activation of Mg by the second heat treatment is offset.

Further, FIG. 5 shows that for the crystal layer composition of Al _0.5 Ga _0.5 N, after performing the first heat treatment for 20 minutes with different holding temperatures, the second holding temperature is further increased. It is a figure which shows the specific resistance after performing a 2nd heat treatment 950 degreeC and holding time as 1 minute. For example, FIG. 5 shows that when the holding temperature in the first heat treatment is 800 ° C., by performing the second heat treatment with a second holding temperature of 950 ° C. and a holding time of 1 minute, As shown, the specific resistance decreases.

  From FIG. 5, it is confirmed that there is a holding temperature range of the first heat treatment that can suitably obtain the effect of the second heat treatment. That is, in the case of FIG. 5, at least the first holding temperature is between 700 ° C. and 850 ° C., so that the effect of reducing the specific resistance in the two-stage heat treatment combined with the second heat treatment can be obtained satisfactorily. I can say that. This is because the first heat treatment at a temperature lower than 700 ° C. does not sufficiently activate Mg even if the second heat treatment is combined, and the first heat treatment at a temperature higher than 850 ° C. Even if it is advantageous in terms of the activation of Mg, it can be said that this also causes the mixing of oxygen into the crystal layer and the depletion of nitrogen, which offsets the effect of the activation of Mg. . It is confirmed by the inventors of the present invention that the first heat treatment in the temperature range as described above is suitable for the other composition ranges.

As described above, according to the present embodiment, a crystal made of Mg-doped Al _x In _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). The layer is subjected to a treatment for holding for 20 minutes or more at a first holding temperature in the range of 700 ° C. to 850 ° C. in a hydrogen-free atmosphere as a first heat treatment, and then no hydrogen is contained as a second heat treatment. In the atmosphere, the specific resistance of the crystal layer can be significantly reduced by performing a treatment that is held at a second heat treatment temperature in the range of 900 ° C. to 1000 ° C. for a short time of 2 minutes or less. That is, good P-type conductivity can be realized in the crystal layer.

(Example 1)
A template substrate as a base substrate was prepared by epitaxially growing an AlN layer (1 μm) on a C-plane sapphire substrate (thickness 400 μm) using MOCVD.

Next, a crystal layer made of Al _x Ga _1-x N was formed to a thickness of 1 μm on the template substrate by using the MOCVO method. At that time, intentional doping is not performed during the growth of the first half of 0.5 μm, and the latter half of 0.5 μm is grown while doping with Mg so that the concentration becomes 1 × 10 ²⁰ / cm ^3. It was. The composition ratio of each crystal layer was x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7. That is, a total of eight types of samples were produced in which crystal layers having different Al composition ratios were formed on the same type of template substrate.

The hole mobility, hole concentration, and specific resistance were measured for each sample thus produced. In the following, when the hole mobility is 8 cm ² / Vs or more, the hole concentration is 5 × 10 ¹⁷ / cm ³ or more, and the specific resistance is about 1 Ωcm or less, good P-type conductivity is obtained. Judge that it has. However, these standards are not absolute, and it goes without saying that there is no problem in actual use even if the numerical values are somewhat inferior depending on the device configuration, usage environment, and the like.

  Thereafter, as a first heat treatment, a heat treatment was performed for 20 minutes at a holding temperature of 800 ° C. in a nitrogen atmosphere, and the hole mobility, the hole concentration, and the specific resistance were measured for each sample after the heat treatment.

  Thereafter, as the second heat treatment, a heat treatment was performed at a holding temperature of 950 ° C. for 1 minute, and hole mobility, hole concentration, and specific resistance were measured for the heat-treated samples.

  The obtained measurement results are shown in Table 1. FIG. 1 illustrates the relationship between the specific resistances shown in Table 1.

  Table 1 shows that hole mobility and hole concentration, which were not obtained only by the first heat treatment, are increased by performing the second heat treatment after performing the first heat treatment on the sample having an Al-rich composition range. I understand that. It is also confirmed that the decrease in specific resistance correlates with these increases.

(Comparative Example 1)
Seven samples (Al _0.5 Ga _0.5 N) in Example 1 where x = 0.5 were prepared, and only the first heat treatment was performed with the first holding temperature being 800 ° C. and different holding times. About the sample after heat processing, the hole mobility, the hole concentration, and the specific resistance were measured, respectively.

  The obtained measurement results are shown in Table 2. FIG. 2 illustrates the specific resistance relationship shown in Table 2.

  From Table 2, it is confirmed that even if only the first heat treatment is performed for a long time, good conductivity cannot be obtained to the extent after the second heat treatment of Example 1. That is, it is confirmed that the second heat treatment as in Example 1 is effective.

(Example 2)
In this example, five samples (Al _0.5 Ga _0.5 N) in the case of x = 0.5 of Example 1 were produced, and the first heat treatment was performed at a first holding temperature of 800 ° C. and a holding time of 1 minute. The second heat treatment was performed at various holding temperatures with a holding time of 1 minute. About the sample after heat processing, the hole mobility, the hole concentration, and the specific resistance were measured, respectively.

  The obtained measurement results are shown in Table 3. FIG. 3 illustrates the relationship between the specific resistances shown in Table 3.

  From Table 3, although high hole mobility and hole concentration are obtained and the specific resistance is remarkably reduced when the second holding temperature is in the range of 900 ° C. to 1000 ° C., the treatment is performed at a lower temperature when the holding temperature is further increased. It is confirmed that only a hole mobility and a hole concentration comparable to those obtained are obtained, and the specific resistance is increased.

  That is, it can be seen that a suitable holding temperature range exists in the second heat treatment.

(Example 3)
In this example, six samples (Al _0.5 Ga _0.5 N) in the case of x = 0.5 in Example 1 were produced, and the first heat treatment was performed at a first holding temperature of 800 ° C. and a holding time of 1 minute. While the second heat treatment was fixed at a holding temperature of 950 ° C., the holding time was variously changed. About the sample after heat processing, the hole mobility, the hole concentration, and the specific resistance were measured, respectively.

  The obtained measurement results are shown in Table 4. FIG. 4 illustrates the specific resistance relationship shown in Table 4.

  From Table 4, it can be seen that when the second retention time is 2 minutes or less, high hole mobility and hole concentration are obtained and the specific resistance is remarkably reduced. However, when the retention time is further increased, the hole mobility and hole concentration are increased. It is confirmed that the concentration decreases and the specific resistance increases.

  That is, it can be seen that a suitable holding time range exists in the second heat treatment.

Example 4
In this example, six samples (Al _0.5 Ga _0.5 N) in the case of x = 0.5 in Example 1 were produced, and the first heat treatment with different holding times and holding times of 20 minutes. Then, a second heat treatment was performed at a holding temperature of 950 ° C. and a holding time of 1 minute. About the sample after heat processing, the hole mobility, the hole concentration, and the specific resistance were measured, respectively.

  The obtained measurement results are shown in Table 5. FIG. 5 illustrates the relationship between the specific resistances shown in Table 5.

  From Table 5, if the first heat treatment is performed at a holding temperature in the range of 700 ° C. to 850 ° C., good conductivity can be obtained by performing the second heat treatment, while the holding temperature in the first heat treatment is the temperature. It is confirmed that the effect of the second heat treatment cannot be sufficiently obtained even if it is too low or too high than the range.

Al _x Ga _1-x N of (0 ≦ x ≦ 1) crystal layers represented by the heat treatment before, after the first heat treatment is a diagram showing a specific resistance after the second heat treatment. The crystal layers represented by Al _0.5 Ga _0.5 N, a first holding temperature of 800 ° C., is a diagram showing changes in specific resistance values after the first heat treatment Chigae retention time variously. The crystal layers represented by Al _0.5 Ga _0.5 N, a first heat treatment 800 ° C., after 20 minutes, is a diagram showing a specific resistance in the case of performing the second heat treatment at different holding temperature conditions. For the crystal layer represented by Al _0.5 Ga _0.5 N, after the first heat treatment was performed at 800 ° C. for 20 minutes, the second holding temperature was set to 950 ° C., and the second heat treatment was performed at various holding times different from each other. It is a figure about a specific resistance. For the crystal layer represented by Al _0.5 Ga _0.5 N, after performing the first heat treatment with different first holding temperatures, the second holding temperature is set to 950 ° C. and the holding time is set to 1 minute. It is a figure which shows the specific resistance at the time of performing.

Claims (13)

This is a method for improving the P-type conductivity in a group III nitride semiconductor of Al _x In _y Ga _{1 -xy} N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) doped with Mg. And
A first heat treatment step of holding the group III nitride semiconductor at a first holding temperature belonging to a temperature range of 700 ° C. to 850 ° C. in an atmosphere containing no hydrogen;
Performing the second heat treatment step of holding the group III nitride semiconductor that has undergone the first heat treatment step at a second holding temperature belonging to a temperature range of 900 ° C. to 1000 ° C. for a short period of 2 minutes or less;
A method for improving the P-type conductivity of an Mg-doped group III nitride semiconductor, characterized in that: A method for improving the P-type conductivity of a Mg-doped group III nitride semiconductor according to claim 1,
Mg-doped group III nitride wherein the group III nitride semiconductor is Al _x In _y Ga _1-xy N (0.4 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) A method for improving the P-type conductivity of a semiconductor. A method for improving the P-type conductivity of an Mg-doped group III nitride semiconductor according to claim 1 or 2,
The method for improving the P-type conductivity of an Mg-doped group III nitride semiconductor, wherein the second holding temperature is 950 ° C. A method for improving the P-type conductivity of an Mg-doped group III nitride semiconductor according to any one of claims 1 to 3,
The holding time at the first holding temperature in the first heat treatment step is 20 minutes or more,
A method for improving the P-type conductivity of an Mg-doped group III nitride semiconductor, characterized in that: A method for improving the P-type conductivity of an Mg-doped group III nitride semiconductor according to any one of claims 1 to 4,
The first holding temperature in the first heat treatment step is 800 ° C .;
A method for improving the P-type conductivity of an Mg-doped group III nitride semiconductor, characterized in that: A method for improving the P-type conductivity of an Mg-doped group III nitride semiconductor according to any one of claims 1 to 5,
The first and second heat treatment steps are performed by heating a semiconductor layer made of the group III nitride semiconductor, which is epitaxially formed on a predetermined underlayer.
A method for improving the P-type conductivity of an Mg-doped group III nitride semiconductor, characterized in that: A method for improving the P-type conductivity of an Mg-doped group III nitride semiconductor according to claim 6,
As the base layer, a template substrate in which an AlN epitaxial film is formed on a sapphire single crystal base material is used.
A method for improving the P-type conductivity of an Mg-doped group III nitride semiconductor, characterized in that: A method for producing a P-type group III nitride semiconductor comprising Al _x In _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1),
A growth step of epitaxially growing the semiconductor layer made of the group III nitride semiconductor by MOCVD while doping Mg on a predetermined underlayer;
A first heat treatment step of holding the semiconductor layer obtained by the growth step at a first holding temperature belonging to a temperature range of 700 ° C. to 850 ° C. in an atmosphere not containing hydrogen;
A second heat treatment step of holding the semiconductor layer that has undergone the first heat treatment step for a short time of 2 minutes or less at a second holding temperature belonging to a temperature range of 900 ° C. to 1000 ° C. in an atmosphere not containing hydrogen;
A method for producing a P-type group III nitride semiconductor comprising: A method for producing a P-type group III nitride semiconductor according to claim 8,
P-type group III nitride wherein the group III nitride semiconductor is Al _x In _y Ga _1-xy N (0.4 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1) Semiconductor manufacturing method. A method for producing a P-type group III nitride semiconductor according to claim 8 or 9, wherein
The method for producing a P-type group III nitride semiconductor, wherein the second holding temperature is 950 ° C. A method for producing a P-type group III nitride semiconductor according to any one of claims 8 to 10,
The holding time at the first holding temperature in the first heat treatment step is 20 minutes or more,
A method for producing a P-type group III nitride semiconductor, characterized in that: A method for producing a P-type group III nitride semiconductor according to any one of claims 8 to 11,
The first holding temperature in the first heat treatment step is 800 ° C .;
A method for producing a P-type group III nitride semiconductor, characterized in that: A method for producing a P-type group III nitride semiconductor according to any one of claims 8 to 12,
As the base layer, a template substrate in which an AlN epitaxial film is formed on a sapphire single crystal base material is used.
A method for producing a P-type group III nitride semiconductor, characterized in that:

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