JP3301345B2 - Method for forming p-type gallium nitride-based compound semiconductor layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a p-type gallium nitride-based compound semiconductor layer used in a light emitting device such as an ultraviolet or blue light emitting laser diode or an ultraviolet or blue light emitting diode.

[0002]

2. Description of the Related Art A blue light emitting device is a ZnS of II-VI group.
e, studies have been carried out using SiC of the IV-IV group, GaN of the III-V group and the like, and recently, among them, a gallium nitride-based compound semiconductor [In _x Al _Y Ga _{1-x -Y} N (0 ≦
X, 0 ≦ Y, X + Y ≦ 1)] have been reported to exhibit relatively excellent light emission at room temperature, and have attracted attention. Blue light emitting device having the nitride semiconductor is essentially the formula on a substrate made of sapphire _{In X Al Y Ga 1-X} -Y N
It has a structure in which epitaxial layers of a nitride semiconductor represented by (0 ≦ X, 0 ≦ Y, X + Y ≦ 1) are sequentially stacked in n-type and i-type or p-type.

As a method of laminating a nitride semiconductor, a metal organic compound vapor deposition method (hereinafter referred to as MOCVD method),
Vapor phase growth methods such as molecular beam epitaxy (hereinafter referred to as MBE) are well known. For example, the method using the MOCVD method will be briefly described. In this method, an organometallic compound gas such as trimethylgallium (TMG), trimethylaluminum (TMA), ammonia or the like is used as a reaction gas in a reaction vessel provided with a sapphire substrate. Is supplied, the crystal growth temperature is maintained at a high temperature of about 900 ° C. to 1100 ° C., and the nitride semiconductor is grown on the substrate. , I-type, or p-type.
In addition to sapphire, the substrate may be SiC, Si, or the like, but sapphire is generally used. Well-known n-type impurities are Si, Ge, and Sn (however, in the case of a nitride semiconductor, they have a property of becoming n-type without doping with an n-type impurity). Cd, B
e, Mg, Ca, Ba and the like.
g and Zn are best known.

Further, as one method of forming a nitride semiconductor by the MOCVD method, if a nitride semiconductor is grown directly on a sapphire substrate at a high temperature, the surface state and crystallinity are significantly deteriorated. Before you do,
Forming a buffer layer made of AlN at a low temperature of about 0 ° C.,
Subsequently, it has been revealed that the crystallinity is remarkably improved by performing growth at a high temperature on the buffer layer (Japanese Patent Application Laid-Open No. 2-229476). In addition, the present inventor has shown in Japanese Patent Application No. 3-89840 that a crystalline nitride semiconductor having better crystallinity can be laminated using GaN as a buffer layer than the conventional method using AlN as a buffer layer.

However, a blue light emitting device having a nitride semiconductor has not yet been put to practical use. This is because a nitride semiconductor cannot be made into a p-type with low resistance, so that a light-emitting element having various structures such as a double hetero structure and a single hetero structure cannot be formed. Even if a nitride semiconductor doped with a p-type impurity is grown by a vapor phase growth method, the obtained nitride semiconductor does not become a p-type and a high-resistance semi-insulating material having a resistivity of 10 ⁸ Ω · cm or more. That is, it was the actual situation that it became i-type. For this reason, at present, only the so-called MIS structure of a blue light emitting element is known, in which a buffer layer, an n-type layer, and an i-type layer are sequentially stacked on a substrate.

[0006]

As means for lowering the resistance of a high-resistance i-type so as to approach the p-type, Japanese Patent Laid-Open No. 2-25 / 1990
No. 7679, a high-resistance i-type gallium nitride compound semiconductor doped with Mg as a p-type impurity is formed in the uppermost layer, and then the surface is irradiated with an electron beam having an accelerating voltage of 6 kV to 30 kV so that about 0.5 μm
A technique for reducing the resistance of a layer has been disclosed. However, this method has a problem that only the penetration depth of the electron beam, that is, the resistance can be reduced only on the very surface, and the entire wafer must be irradiated while scanning the electron beam, so that the resistance cannot be reduced uniformly in the plane. there were.

Therefore, an object of the present invention is to make a nitride semiconductor doped with a p-type impurity a low-resistance p-type, furthermore, the resistance value is uniform over the entire wafer regardless of the film thickness, and the light-emitting element can be a double heterostructure. An object of the present invention is to provide a method for forming a p-type gallium nitride-based compound semiconductor layer having a single heterostructure.

[0008]

According to the method of the present invention, magnesium acts as an acceptor by a vapor phase growth method using an organometallic compound as a reaction gas.
Forming a gallium nitride-based compound semiconductor layer containing hydrogen bonded to magnesium and preventing hydrogen bonded to magnesium from the gallium nitride-based compound semiconductor layer containing hydrogen bonded to magnesium. Is thermally dissociated to form a gallium nitride-based compound semiconductor layer.
An annealing step of extracting hydrogen from the entire region in the depth direction to form a low-resistance p-type gallium nitride-based compound semiconductor layer.

Further, in the method for forming a p-type gallium nitride-based compound semiconductor layer according to claim 2 of the present invention, a p-type gallium nitride-based compound semiconductor layer is formed on a buffer layer.

In particular, the present invention provides a method for growing a gallium nitride-based compound semiconductor layer containing magnesium bonded with hydrogen on a gallium nitride-based compound semiconductor layer containing magnesium, followed by annealing to form a gallium nitride-based compound semiconductor layer containing magnesium. Hydrogen bonded to magnesium is removed from the compound semiconductor layer. Note that, in the present invention, the term “hydrogen removed from a gallium nitride-based compound semiconductor containing magnesium” does not necessarily mean that all of the hydrogen is removed, but that part of the hydrogen is removed is within the scope of the present invention. Needless to say,

Annealing (annealing: heat treatment) may be performed in a reaction vessel after growing a gallium nitride-based compound semiconductor layer doped with a p-type impurity, or a wafer may be taken out of the reaction vessel and used exclusively for annealing. This may be performed using an apparatus. The annealing atmosphere is performed in a vacuum, in an atmosphere of an inert gas such as N ₂ , He, Ne, or Ar, or in a mixed gas atmosphere thereof. Preferably, nitrogen is pressurized at a temperature higher than the decomposition pressure of the gallium nitride-based compound semiconductor at the annealing temperature. Perform in an atmosphere. This is because pressurization in a nitrogen atmosphere has an effect of preventing N in the gallium nitride-based compound semiconductor from decomposing and coming out during annealing.

For example, in the case of GaN, the decomposition pressure of GaN is 8
About 0.01 atm at 00 ° C, about 1 atm at 1000 ° C, 11
It is about 10 atmospheres at 00 ° C. Therefore, when annealing a gallium nitride-based compound semiconductor at 400 ° C. or higher,
More or less decomposition of the gallium nitride-based compound semiconductor occurs, and its crystallinity tends to deteriorate. Accordingly, decomposition can be prevented by pressurizing with nitrogen as described above.

The annealing temperature is, for example, 400 ° C.
The above is carried out at preferably 700 ° C. or more, for 1 minute or more, preferably for 10 minutes or more. Even at a temperature of 1000 ° C. or higher, decomposition can be prevented by pressurizing with nitrogen as described above, and as described later, a stable p-type gallium nitride-based compound semiconductor having excellent crystallinity can be obtained. .

As a means for suppressing the decomposition of the gallium nitride-based compound semiconductor during the annealing, a cap layer may be further formed on the gallium nitride-based compound semiconductor layer doped with a p-type impurity, followed by annealing. Good. The cap layer is a protective film, which is formed on a gallium nitride-based compound semiconductor doped with a p-type impurity, and then annealed at 400 ° C. or more to reduce the pressure, not to mention the pressure. Even under normal pressure, the gallium nitride-based compound semiconductor can be made into a low-resistance p-type without decomposing.

In order to form a cap layer, a gallium nitride-based compound semiconductor layer doped with a p-type impurity may be formed and then formed in a reaction vessel, or a wafer may be taken out of the reaction vessel. It may be formed by another crystal growth apparatus such as a plasma CVD apparatus. As the material of the cap layer, any material can be used as long as it is a material that can be formed on the gallium nitride-based compound semiconductor and is stable at 400 ° C. or higher, and preferably Ga _x Al ₁ -XN.
(Where 0 ≦ X ≦ 1), Si ₃ N ₄ , and SiO ₂ can be given, and the type of material is appropriately selected depending on the annealing temperature. The thickness of the cap layer is usually 0.01 to 5 μm.
m. When the thickness is less than 0.01 μm, the effect as a protective film cannot be sufficiently obtained. When the thickness is more than 5 μm, it takes time to remove the cap layer by etching after annealing and expose the p-type gallium nitride-based compound semiconductor layer. This is not economical.

[0016]

FIG. 1 is a diagram showing that a gallium nitride-based compound semiconductor layer doped with a p-type impurity changes to a low-resistance p-type by annealing. However, this figure shows the MO
First, a GaN buffer layer is formed on a sapphire substrate using a CVD method, and a GaN layer is formed to a thickness of 4 μm while doping Mg as a p-type impurity thereon. Then, the wafer is taken out and the temperature is changed. FIG. 3 is a diagram in which holes are measured on a wafer after annealing is performed for 10 minutes in a nitrogen atmosphere, and resistivity is plotted as a function of annealing temperature.

As can be seen from this figure, when the annealing time is set to 10 minutes, the resistivity of the Mg-doped GaN layer rapidly decreases from around 400 ° C.
It shows almost constant low-resistance P-type characteristics from 00 ° C.
The effect of annealing appears. The GaN layer not annealed and the Ga annealed at 700 ° C. or more
The hole measurement results of the N layer show that the GaN layer before annealing has a resistivity of 2 × 10 ⁵ Ω · cm and a hole carrier concentration of 8 × 1.
0 ¹⁰ / cm ³ , whereas G after annealing
The aN layer has a resistivity of 2Ω · cm and a hole carrier concentration of 2 × 1.
0 ¹⁷ / cm ³ .

Further, the 4 μm GaN layer annealed at 700 ° C. is etched to a thickness of 2 μm,
As a result of the hole measurement, a hole carrier concentration of 2 × 10
¹⁷ / cm ³ and resistivity ³ Ω · cm, almost the same values as before etching. That is, the GaN layer doped with the P-type impurity becomes low-resistance p-type uniformly in the depth direction over the entire region by annealing.

FIG. 2 shows a wafer obtained by forming a GaN buffer layer and a Mg-doped GaN layer of 4 μm on a sapphire substrate by MOCVD.
Annealing was performed for 20 minutes in a nitrogen atmosphere at 000 ° C., and the p-type GaN layers of the wafer (a) performed under a pressure of 20 atm and the wafer (b) performed at an atmospheric pressure were respectively subjected to H annealing.
FIG. 3 is a diagram illustrating irradiation with an e-Cd laser as an excitation light source, and comparison of crystallinity with photoluminescence intensity thereof.
The higher the blue luminescence intensity of the photoluminescence at 450 nm, the better the crystallinity can be evaluated.

As shown in FIG. 2, when annealing is performed at a high temperature of 1000 ° C. or higher, the crystallinity of the GaN layer tends to be degraded due to the thermal decomposition. P-type G with excellent crystallinity
An aN layer is obtained.

FIG. 3 shows a wafer (c) in which a GaN buffer layer and a 4 μm Mg-doped GaN layer are formed on a sapphire substrate, and a 0.5 μm AlN layer as a cap layer thereon. The wafer (d) grown at a thick thickness is then subjected to a pressure of 1000
After annealing for 20 minutes in a nitrogen atmosphere at ℃
P exposed by removing the cap layer by etching
FIG. 4 is a diagram showing the crystallinity of a GaN layer in comparison with the photoluminescence intensity.

As shown in FIG. 3, the p-type GaN layer (c) annealed without growing the cap layer is decomposed when the annealing is performed at a high temperature. Becomes weaker. However, by growing the cap layer (in this case, AlN), the AlN of the cap layer is decomposed but the p-type GaN layer is not decomposed, so that the emission intensity is still strong.

The reason why a low-resistance p-type gallium nitride-based compound semiconductor can be obtained by annealing is presumed to be as follows.

That is, in growing a gallium nitride-based compound semiconductor layer, NH ₃ is generally used as an N source, and it is considered that the NH ₃ is decomposed during growth to form atomic hydrogen. This atomic hydrogen is combined with Mg doped as an acceptor impurity to form Mg.
Is considered to prevent the p-type impurity from acting as an acceptor. Therefore, the gallium nitride-based compound semiconductor doped with the p-type impurity after the reaction shows high resistance.

However, by performing annealing after the growth, the hydrogen bonded in the form of Mg—H is thermally dissociated and exits from the gallium nitride-based compound semiconductor layer doped with the p-type impurity. Since the p-type impurity acts as an acceptor, a low-resistance p-type gallium nitride-based compound semiconductor can be obtained. Hydrogen bonded in the form of Mg-H is thermally dissociated and exits from the gallium nitride-based compound semiconductor layer. Since hydrogen bonded to magnesium is removed by annealing, it is not preferable to use a gas containing a hydrogen atom such as NH ₃ or H ₂ in the annealing atmosphere. Also, in the cap layer,
It is not preferable to use a material containing a hydrogen atom for the above reasons.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. [Example 1] First, a well-cleaned sapphire substrate is placed on a susceptor in a reaction vessel. After evacuating the container, the substrate is heated at 1050 ° C. for 20 minutes while flowing hydrogen gas to remove oxides on the surface. Thereafter, the temperature was cooled to 510 ° C., and at 510 ° C., TMG gas was
^3.10-6 mol / min, ammonia gas as N source
0 liter / min, hydrogen gas 2.0
While flowing at a rate of 1 liter / min, the GaN buffer
It is grown to a thickness of Å.

Next, only the TMG gas was stopped and the temperature was increased to 103.
After the temperature was raised to 0 ° C., TMG gas was again supplied to 54 × 10 5
^-6 mol / min, Cp ₂ Mg (cyclopentadienyl magnesium) gas is grown at a flow ^rate of 3.6 × 10 ⁻⁶ mol / min for 60 minutes to grow GaN doped with Mg.
The layer is grown to a thickness of 4 μm.

After cooling, the wafer grown above was taken out of the reactor, placed in an annealing apparatus, and annealed at 800 ° C. for 20 minutes in a nitrogen atmosphere at normal pressure.

As a result of the hole measurement of the p-type GaN layer obtained by annealing, the p-type GaN layer showed excellent p-type characteristics such as a resistivity of 2 Ω · cm and a hole carrier concentration of 2 × 10 ¹⁷ / cm ³ .

Example 2 In Example 1, after growing a Mg-doped GaN layer, the Cp ₂ Mg gas was stopped, and then G was used as a cap layer.
An aN layer is grown to a thickness of 0.5 μm.

In the same manner as in Example 1, the annealing apparatus is used under the normal pressure under a mixed gas atmosphere of nitrogen and argon.
Anneal at 0 ° C. for 20 minutes. Thereafter, the layer of 0.5 μm was removed from the surface by dry etching,
The cap layer was removed to expose the p-type GaN layer, and a hole measurement was performed in the same manner. As a result, excellent p-type characteristics were exhibited with a resistivity of 2 Ω · cm and a carrier concentration of 1.5 × 10 ¹⁷ / cm ³ . Note that the photoluminescence blue light emission intensity at 450 nm was about four times stronger than that of Example 1.

Example 3 In Example 1, after the Mg-doped GaN layer was grown, the wafer was taken out of the reaction vessel, and the wafer was taken out in an annealing apparatus at 20 atm and 800 ° C. in a nitrogen atmosphere.
Anneal for a minute. As a result of Hall measurement, the resistivity was 2 Ω · cm, and the carrier concentration was 2.0 × 10 ¹⁷ / cm.
³ showing excellent p-type characteristics and 4 of photoluminescence.
The emission intensity at 50 nm was about 4 times stronger than that of Example 1.

Example 4 In Example 1, after growing a Mg-doped GaN layer, the wafer was taken out of the reaction vessel and plasma CVD was performed.
Using a device, a SiO ₂ layer having a thickness of 0.5 μm is formed thereon as a cap layer.

In the annealing apparatus, a nitrogen atmosphere,
Anneal at atmospheric pressure at 1000 ° C. for 20 minutes.
Thereafter, the SiO ₂ cap layer was removed with hydrofluoric acid, and the p-type GaN layer was exposed.
Resistivity 2Ω · cm, carrier concentration 2.0 × 10 ¹⁷ / c
It showed m ³ and excellent p-type characteristics. The emission intensity of photoluminescence at 450 nm is about 2 times lower than that obtained by annealing under the same conditions without forming a cap layer.
It was 0 times stronger.

Example 5 In Example 1, after the Mg-doped GaN layer was grown, the Cp ₂ Mg gas was stopped and TMA gas was newly added at 6 × 10 ⁻⁶ mol / min and SiH ₄ (monosilane) ) A gas of 2.2 × 10 ⁻¹⁰ mol / min was flowed for 20 minutes,
The n-type Ga _0.9 Al _0.1 N layer doped with i is
Grow to a thickness of 8 μm.

The TMG gas, TMA gas, and SiH ₄ gas are stopped, and cooled to room temperature while flowing hydrogen gas and ammonia gas. Then, the wafer is taken out, placed in an annealing apparatus, and held at 700 ° C. for 20 minutes in a nitrogen atmosphere. And perform annealing.

In this manner, the p-type G
A device having a single hetero structure in which an aN layer and an n-type Ga _0.9 Al _0.1 N layer were sequentially stacked was obtained. The gallium nitride-based compound semiconductor layer of this device was replaced with n-type Ga
A part of the _0.9 Al _0.1 N layer is etched to form p-type Ga.
After exposing a part of the N layer and attaching an ohmic electrode to each layer, the layer was cut into chips using a dicing saw.
Electrodes were removed from the exposed n-type layer and p-type layer, and then molded to produce a blue light emitting diode. The characteristics of this light-emitting diode were such that blue light was emitted with a light emission output of 90 μW at a forward current of 20 mA and a forward voltage of 5 V, and the peak wavelength was 430 nm. This light emission output is a high value which has not been reported in the past as the output of the blue light emitting diode.

On the other hand, when a light emitting diode having the same single heterostructure was manufactured without annealing, the light emitting diode had a forward voltage of about 60 V at a forward current of 20 mA, and the light emission was slightly yellow. It only glowed in color and was immediately broken, and the luminescence output could not be measured.

Embodiment 6 A GaN buffer layer is formed on a sapphire substrate to a thickness of 200 Å in the same manner as in Embodiment 1.

Next, only the TMG gas was stopped, and the temperature was changed to 103.
After the temperature was raised to 0 ° C., TMG gas was
^-6 mol / min and a new SiH ₄ (monosilane) gas flowing at 2.2 × 10 ⁻¹⁰ mol / min for 60 minutes to grow the Si-doped n-type GaN layer to a thickness of 4 μm. grow up.

Subsequently, the SiH ₄ gas is stopped, and the Cp ₂ Mg gas is grown at a flow ^rate of 3.6 × 10 ⁻⁶ mol / min for 30 minutes to grow the Mg-doped GaN layer to a thickness of 2.0 μm.

After stopping the TMG gas and the Cp ₂ Mg gas and cooling to room temperature while flowing hydrogen gas and ammonia gas, the gas flowing into the reaction vessel is replaced with nitrogen gas, and the gas in the reaction vessel is cooled while flowing nitrogen gas. The temperature is raised to 1000 ° C. and held in the reaction vessel for 20 minutes for annealing.

When the device thus obtained was used as a light emitting diode to emit light, it showed blue light emission having an emission peak near 430 nm and an emission output of 50 μm at 20 mA.
W, and the forward voltage was also 4 V at 20 mA. In addition, when a device having the same structure was produced without annealing and used as a light emitting diode, the light emitting device emitted a slightly yellow light at 20 mA, and the diode was immediately broken.

[0044]

The present invention realizes the following extremely excellent features. Until now, even if a p-type impurity is doped, a gallium nitride-based compound semiconductor layer that was extremely difficult to be made into a low-resistance p-type layer can be annealed into a low-resistance p-type gallium nitride-based compound semiconductor layer, With this p-type gallium nitride-based compound semiconductor layer, a light-emitting element having extremely excellent light-emitting characteristics can be realized. In particular, the present invention has a feature that the gallium nitride-based compound semiconductor layer containing magnesium is made into a p-type by a very simple method of annealing, so that the gallium nitride-based compound semiconductor and the light emitting device can be mass-produced at a very low cost. There is. With electron beam irradiation,
Gallium nitride based compound semiconductor layer containing magnesium
In the conventional light emitting device that has been shaped, the electron beam is accelerated to collide with the surface of the gallium nitride-based compound semiconductor layer containing magnesium. The semiconductor layer which is made p-type by the electron beam is made p-type by the electron beam focused on the spot. The semiconductor layer to be converted into a p-type spot needs to be scanned with an electron beam in order to make the entire gallium nitride-based compound semiconductor layer having a large area p-type. Therefore, it takes time to make the gallium nitride-based compound semiconductor layer into a p-type in a wide area, and it is not possible to efficiently make a large number of gallium nitride-based compound semiconductor layers into a p-type. Further, in a light-emitting element in which a gallium nitride-based compound semiconductor layer is converted into a p-type with an electron beam, it is necessary to dispose a gallium nitride-based compound semiconductor containing magnesium in a vacuum and irradiate the electron beam. For this reason, the conventional light-emitting element needs to be placed in an airtightly sealed container and evacuated in order to make the gallium nitride-based compound semiconductor layer into a p-type, and it is extremely limited locally by an electron beam. Since the narrow region is made p-type, the gallium nitride based compound semiconductor layer containing magnesium can be efficiently formed,
Further, a plurality of wafers on which gallium nitride-based compound semiconductor layers containing magnesium are grown cannot be stacked to form a p-type together. However, according to the present invention, the gallium nitride-based compound semiconductor layer containing magnesium is annealed to remove hydrogen bonded to magnesium to form a p-type, so that the gallium nitride-based compound semiconductor layer containing magnesium is grown. Multiple wafers
It realizes a truly ideal feature that it can be made p-type easily and easily, very inexpensively and efficiently, and has excellent light emitting characteristics.

The present invention has a feature that the entire surface of a gallium nitride-based compound semiconductor layer containing magnesium can be made uniformly p-type. That is, since the gallium nitride-based compound semiconductor layer containing magnesium is annealed to remove hydrogen bonded to magnesium and become p-type, the entire gallium nitride-based compound semiconductor layer is uniformly formed during annealing. This is because it becomes p-type by heating. A conventional gallium nitride-based compound semiconductor light-emitting device in which a gallium nitride-based compound semiconductor layer containing magnesium is converted into a p-type by irradiating an electron beam is scanned by an electron beam that can only be locally changed into a p-type, and the entire surface is p-type. Since it is formed into a mold, it is extremely difficult to make the entire surface uniform p-type. In particular, if the interval between electron beams scanned linearly is increased in order to increase the efficiency of p-type conversion, a problem arises in that the p-type cannot be reliably formed at the boundary of the scanning line. Conversely, if the interval between the electron beams scanned linearly is narrowed, the gallium nitride-based compound semiconductor layer having a large area cannot be efficiently made into a p-type. In the present invention, the gallium nitride-based compound semiconductor layer containing magnesium is not locally p-type. Annealing and p
The entire surface of the gallium nitride-based compound semiconductor layer is heated, and hydrogen bonded to magnesium is dissociated by heat to be uniformly p-type. This is extremely important when manufacturing a semiconductor wafer. The gallium nitride compound semiconductor light emitting device is large,
Since a wafer is manufactured and cut into small pieces to manufacture a gallium nitride-based compound semiconductor light emitting device chip, if the gallium nitride-based compound semiconductor layer is not uniformly p-type, the yield of the manufactured chip is reduced. This is because it is significantly reduced.

According to the present invention, the gallium nitride-based compound semiconductor layer containing magnesium is deeply p-type and more uniformly p-type as a whole, and the light-emitting element realizes excellent light-emitting characteristics. On the other hand, in a conventional gallium nitride-based compound semiconductor light emitting device in which a semiconductor layer containing magnesium is made p-type with an electron beam, the semiconductor layer containing magnesium is made the uppermost layer, and only the extreme surface is made p-type. Has not been reduced in resistance. This is because the accelerated electron beam cannot be deeply injected. The present invention provides a gallium nitride-based compound semiconductor containing magnesium as a whole,
Since heat is applied by annealing to remove hydrogen bonded to magnesium to form a p-type, the entire gallium nitride-based compound semiconductor layer containing magnesium is heated to be more uniformly p-type, resulting in extremely high brightness. A light emitting element can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between an annealing temperature and a resistivity according to an embodiment of the present invention.

FIG. 2 is a diagram showing the crystallinity of a p-type GaN layer according to one embodiment of the present invention in comparison with photoluminescence intensity.

FIG. 3 is a diagram showing the crystallinity of a p-type GaN layer according to one embodiment of the present invention in comparison with photoluminescence intensity.

Continuation of front page (56) References JP-A-5-183189 (JP, A) JP-A-3-218625 (JP, A) Japanese Journal of Applied Physics, Japan, Vol. 30, No. 10A, p L1708-L1711 Inst. Phys. Conf. Ser. No. 106, Chapter 8, p. 575-p. 580 (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 33/00 H01L 21/205 H01L 21/324 H01S 5/00-5/50

Claims (2)

(57) [Claims] An organic metal compound is used as a reaction gas.
By using the vapor phase growth method, magnesium, which is a p-type impurity
With magnesium that prevents it from acting as an acceptor
A step of forming a gallium nitride-based compound semiconductor layer containing bonded hydrogen, thermally dissociated hydrogen bonded to the magnesium
Low resistance p-type nitride gas over the entire region and the gallium nitride-based compound out of the semiconductor layer or al Hydrogen <br/> seek direction uniformly Te
Method of forming a potassium compound p-type gallium nitride-based compound you Yes <br/> a higher annealing Engineering of forming a semiconductor semiconductor layer. 2. The method for forming a p-type gallium nitride-based compound semiconductor layer according to claim 1, wherein the p-type gallium nitride-based compound semiconductor layer is formed on the buffer layer.