JPH10112438A - Method for growing p-type nitride iii-v compound semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for growing a p-type nitride III-V compound semiconductor which has less crystal defects and good quality. SOLUTION: A MOCVD device 10 for implementing this method has a reaction tube 14 having inside thereof a suscepter 12 holding a substrate W, and a bubbler 20A housing TMG(trimethylgallium) and adapted for supplying a TMG gas to the reaction tube 14 through a supply line 18 by bubbling with a hydrogen gas. The substrate W is set in the reaction tube 14, and the temperature is raised to 1000 deg.C. Then, a hydrogen gas is supplied to the bubbler 20A, thereby introducing the TMG gas into the reaction tube 14. A GaN:C crystal to which a carbon atom as a p-type dopant is introduced is epitaxially grown on the substrate W. As a result, a GaN:C crystal of good quality having less crystal defects is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a p-type nitride-based II
The present invention relates to a method for growing an IV group compound semiconductor, and more particularly, to a method for growing a p-type nitride III-V compound semiconductor having few crystal defects.

[0002]

2. Description of the Related Art In order to perform recording and reproduction with high density and high resolution on an optical large-capacity recording medium such as an optical disk and a magneto-optical disk, a laser beam having a short wavelength is required. Therefore, in recent years, short-wavelength semiconductor lasers that emit green, blue or ultraviolet light have been actively developed. As a compound semiconductor forming such a laminated structure of a semiconductor laser device in a short wavelength region, for example, "Jpn. J. Appl. Phys. 3"
0 (1991) L1998 ",
Nitride III- such as GaN, AlGaN and InGaN
Group V compound semiconductors are receiving attention. In particular, GaN is
Since the bandgap at room temperature is about 3.4 eV, and it is robust and chemically stable, it is expected to be applied to light receiving and emitting devices in the blue and ultraviolet regions. There are p-type and n-type nitride-based III-V compound semiconductors, and p-type nitride-based II
Group IV compound semiconductors have conventionally been prepared by converting a Group III element such as Ga into a Group II metal by metal organic chemical vapor deposition (MOVPE).
It is obtained by growing a crystal while partially substituting a group element such as Mg or Zn.

[0003]

However, since the equilibrium vapor pressure of nitrogen is extremely high, nitrogen atoms are easily desorbed from the crystal during the growth of the nitride III-V compound semiconductor. Crystals with a large amount of growth grow,
There is a problem that device characteristics are not good. In view of the above circumstances, an object of the present invention is to provide a method for growing a high-quality p-type nitride-based III-V compound semiconductor having few crystal defects.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventor has found that in growing a p-type nitride III-V compound semiconductor, a group II element such as Mg or Zn is used as a p-type dopant. Rather than using the conventional method of replacing group III element atoms with group II element atoms,
Using carbon which is a Group IV element as a type dopant,
It is easier to control the crystal growth by substituting a nitrogen atom which is easily desorbed with a carbon atom, in other words, by introducing a p-type dopant atom into a vacant portion formed by desorption, and thus a high-quality p-type nitride-based material. The present inventors have found that a group III-V compound semiconductor can be obtained, and have completed the present invention.

In order to achieve the above object, a p-type nitride III-V compound semiconductor according to the present invention comprises a raw material having a group III element of the periodic table, a raw material having a group V element, and a p-type nitride semiconductor. P-type nitride III-
In the method of growing a group V compound semiconductor, a substance having a carbon atom belonging to a group IV element is used as a p-type dopant, and a nitrogen atom of a group V element constituting the nitride III-V compound semiconductor is converted to carbon. It is characterized by substitution with an atom. P-type nitride III-V according to the present invention
The group III compound semiconductor can be applied to all p-type nitride III-V group compound semiconductors. In the present invention, a nitrogen atom which is easily desorbed during crystal growth is replaced with a carbon atom of a group IV element. As a result, the amount of missing nitrogen atoms is reduced as a result, and a high-quality p-type nitride III-V compound semiconductor is realized.

A preferred embodiment of the present invention comprises a step of forming a low-temperature buffer layer on a substrate, and a step of forming a p-type nitride III-V
Heating the substrate to a temperature range suitable for epitaxial growth of a group III compound semiconductor, and a source gas containing a group III element, a source gas containing a group V element, and a source gas containing carbon atoms on the substrate. Introduce p-type nitride III-V
A step of epitaxially growing a group III compound semiconductor. The source gas containing carbon atoms is a substance consisting of carbon and hydrogen, for example, C _n H _{2n + 2} (1
≦ n ≦ 5), C _n H _2n (2 ≦ n ≦ 5) or C _n H _2n−2 (2
When at least one kind of substance represented by ≦ n ≦ 5) is included, a high-quality crystal having a carbon atom as a p-type dopant can be grown. C _n H _{2n + 2} is, for example, methane, ethane, propane or butane.

As a specific example of the preferred embodiment,
Epitaxial growth using trimethylgallium gas or triethylgallium gas as a source gas containing a Group III element, ammonia as a source gas containing a Group V element, and butane gas (C ₄ H ₁₀ ) as a source gas containing carbon atoms, p A GaN: C crystal having few crystal defects and having carbon atoms as a type dopant can be obtained.

Further, as a raw material gas containing carbon, ROH
A source gas containing an alcohol represented by (R is any alkyl group) or a source gas composed of an organic compound in which at least one group having a molecular weight greater than 14 is bonded to a nitrogen atom. A good quality crystal can be grown.

Examples of organic compounds include propylamine, isopropylamine, butylamine, isobutylamine,
It is at least one amine compound selected from the group consisting of primary amines including tertiary butylamine, monomethylhydrazine, and ethyl azide. Another example of an organic compound is a secondary amine, including dipropylamine, diisopropylamine, dibutylamine, diisobutylamine, ditertiarybutylamine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, and secondary butylamine. At least one amine compound selected from the group consisting of: Still another example of the organic compound is tripropylamine, triisopropylamine, tributylamine, triisobutylamine, tritertiarybutylamine, trisecondary butylamine, triallylamine, triethylamine, diisopropylmethylamine, dipropylmethylamine, dibutylmethylamine. It is at least one type of amine compound selected from the group consisting of amines, diisobutylmethylamine, disecondary butylmethylamine, and tertiary amines including ditertiarybutylmethylamine.

Using the method of the present invention, a p-type nitride III-
When growing a group V compound semiconductor, the growth of the crystal is easily controlled by the metal organic chemical vapor deposition method or the molecular beam epitaxy method, so that a high-quality crystal is easily obtained.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Example In this example, a p-type nitride III-V compound semiconductor having carbon atoms introduced as a p-type dopant is epitaxially grown by the method of the present invention. FIG.
Shows the configuration of the MOCVD apparatus used in this embodiment.

As shown in FIG. 1, a MOCVD apparatus 10 includes a reaction tube 14 having a susceptor 12 for holding a substrate W therein, and trimethylgallium (TMG) and triethylgallium, which are organic metal materials containing a group III element. (TEG), and the TMG is supplied to the reaction tube 14 via the supply line 18 by bubbling with hydrogen gas.
Two bubblers 20A and 20B for supplying gas or TEG gas, respectively, and the bubbler 20A and B and the reaction tube 14 by purifying hydrogen gas and using high-purity hydrogen gas as carrier gas.
And a hydrogen purifier 22 for supplying to the vent line 26. Further, a cylinder 23 containing ammonia as a nitrogen raw material and supplying ammonia to the reaction tube 14 or the vent line 26 via the supply line 21 and a butane gas as a raw material gas having carbon atoms via the supply line 25 is provided. And a cylinder 27 for supplying butane gas to the reaction tube 14 or the vent line 26. Further, mass flow controllers 24 </ b> A to 24 </ b> D for controlling the flow rate of the hydrogen gas are provided in each line connected to the bubblers 20 </ b> A and 20 </ b> B, the supply line 18, and the vent line 26 from the hydrogen purifier 22. In addition, mass flow controllers 24E and F for controlling the flow rates of ammonia and butane gas are provided in the supply line 21 and the supply line 25, respectively.

Switching valves V1, V2 and switching valves V3, V4 are provided between the bubbler 20A and the supply line 18 and the vent line 26, and between the bubbler 20B and the supply line 18 and the vent line 26, respectively. Then, by switching them, from the bubbler 20A, B to the reaction tube 14 or the vent line 26,
The gas destination can be switched. Similarly, switching valves V5 and V6 are provided between the supply line 21 and the supply line 18 and the vent line 26, respectively, and by switching these valves, ammonia is supplied to the supply line 18 or the vent line 26. The destination can be switched. Further, switching valves V7 and V8 are provided between the supply line 25, the supply line 18 and the vent line 26, respectively, and by switching between them, the butane gas is similarly supplied to the supply line 18 or the vent line 26. The destination can be switched.

In this embodiment, first, a substrate W made of Al ₂ O ₃ (sapphire) having a c-plane formed on its surface is placed on a susceptor 12 in a reaction tube 14 with the c-plane facing upward.
Next, the high-purity hydrogen gas purified by the hydrogen purifier 22 is supplied into the reaction tube 14 while controlling the flow rate by the mass flow controller 24C to make a hydrogen gas atmosphere, and the substrate W is set to 1
Heating was performed at 100 ° C. to perform thermal etching for 10 minutes. Next, the temperature of the substrate was lowered to 600 ° C., and TMG was supplied as a Ga raw material at a flow rate of 100 μmol / min, and ammonia was supplied as a nitrogen raw material at a flow rate of 20 SLM into the reaction tube 14 to form a low-temperature buffer layer (GaN layer 28).

Next, while supplying only ammonia,
The temperature of the substrate W is raised to 1000 ° C., which is a preferable temperature for growing a GaN crystal, and hydrogen gas is supplied to the bubbler 20A to cause
MG gas and butane gas were flowed at a flow rate of 100 μmol /
It was further introduced into the reaction tube 14 at min and 5 sccm. As a result, as shown in FIG. 2, the GaN: C crystal 30 into which carbon atoms were introduced as a p-type dopant could be epitaxially grown on the substrate W. Note that, instead of introducing the TMG gas, hydrogen gas is supplied to the bubbler 20B and the TEG gas is introduced into the reaction tube 14, whereby the epitaxial growth can be performed similarly.

Next, the GaN: C crystal 30 is
Was analyzed by FIG. 3 shows the depth position from the surface of the GaN: C crystal 30 obtained by the SIMS measurement,
It is a graph which shows the relationship between the Ga density at the depth position, and the ion count number showing the density of the introduced carbon atom. It can be seen that carbon atoms have been introduced over a depth of 2 μm or more. As a result of measuring the number of holes, the GaN: C crystal 30 has 8 × 10 ¹⁶ holes / cm ³ , and the p-type nitride III-
It was confirmed that it grew into a group V compound semiconductor.

In this embodiment, the crystal was grown by introducing butane gas and substituting the nitrogen atom, which is a group V element, which is easily desorbed during crystal growth, with the carbon atom, which is a group IV element. As a result, the amount of missing nitrogen atoms during crystal growth can be relatively suppressed as compared with the related art, and therefore, a high-quality p-type nitride III-V compound semiconductor can be grown.

[0018]

According to the present invention, by using a substance having a carbon element as a p-type dopant, a p-type nitride III-V compound semiconductor is formed, and a p-type nitride III-V compound semiconductor is easily removed during crystal growth. Certain nitrogen atoms have been replaced by carbon atoms, which are Group IV elements. This makes it possible to relatively and consequently suppress the missing amount of nitrogen atoms when growing a crystal, so that a high-quality p-type nitride III-V compound semiconductor with few crystal defects can be grown. Can be. As a preferred example, trimethylgallium gas or triethylgallium gas as a source gas containing a Group III element, ammonia as a source gas containing a Group V element, and butane gas as a source gas containing carbon are used to grow crystals. I have. Thereby, it is possible to grow a GaN: C crystal having few crystal defects into which carbon atoms are introduced as a p-type dopant.

[Brief description of the drawings]

FIG. 1 shows the M used in carrying out the method of the embodiment of the present invention.
It is a schematic diagram which shows the structure of an OCVD apparatus.

FIG. 2 is a cross-sectional view of a GaN: C crystal of the present embodiment.

FIG. 3 is a graph showing the relationship between the depth position from the surface of the GaN: C crystal of the present example and the Ga density and the introduced carbon atom density at that position.

[Description of Signs] 10: MOCVD apparatus, 12: susceptor, 14:
Reaction tube, 16 light source for light irradiation, 18 supply line,
20A, B ... bubbler, 21 ... supply line, 22 ...
... hydrogen purifier, 23 ... cylinders, 24A-D ... mass flow controller, 25 ... supply line, 26 ... vent line, 27 ... cylinder, 28 ... low temperature buffer layer (GaN layer), 30 ... GaN : C crystal.

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[Procedure amendment]

[Submission date] January 13, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0002

[Correction method] Change

[Correction contents]

[0002]

2. Description of the Related Art In order to perform recording and reproduction with high density and high resolution on an optical large-capacity recording medium such as an optical disk and a magneto-optical disk, a laser beam having a short wavelength is required. In recent years, green, the development of short wavelength semiconductor laser of blue light or ultraviolet light to the light conditions is active. As a compound semiconductor forming such a laminated structure of a semiconductor laser device in a short wavelength region, for example, "Jpn. J. Appl. Phys. 3"
0 (1991) L1998 ",
Nitride III- such as GaN, AlGaN and InGaN
Group V compound semiconductors are receiving attention. In particular, GaN is
Since the bandgap at room temperature is about 3.4 eV, and it is robust and chemically stable, it is expected to be applied to light receiving and emitting devices in the blue and ultraviolet regions. There are p-type and n-type nitride-based III-V compound semiconductors, and p-type nitride-based II
I-V group compound semiconductors, conventionally, metal organic chemical vapor deposition (MO CVD) method, a group III element such as Ga II
It is obtained by growing a crystal while partially substituting a group element such as Mg or Zn.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

Examples of organic compounds include propylamine, isopropylamine, butylamine, isobutylamine and the like.
Primary amines and tertiary butyl amines
Select from the group consisting of tylhydrazine and ethyl azide
At least one compound . Another example of an organic compound is a secondary amine, including dipropylamine, diisopropylamine, dibutylamine, diisobutylamine, ditertiarybutylamine and secondary butylamine.
, 1,1-dimethylhydrazine and 1,2-dimethylhydrazine
At least one compound selected from the group consisting of drazines
It is a compound. Still another example of the organic compound is tripropylamine, triisopropylamine, tributylamine, triisobutylamine, tritertiarybutylamine, trisecondary butylamine, triallylamine, triethylamine, diisopropylmethylamine, dipropylmethylamine, dibutylmethylamine. amine, diisobutyl methyl a amine, a di-sec-butyl-methyl-amine, and at least one amine compound selected from the group consisting of tertiary amines including ditertiary butyl methyl amine.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction contents]

In this embodiment, first, a substrate W made of Al ₂ O ₃ (sapphire) having a c-plane formed on its surface is placed on a susceptor 12 in a reaction tube 14 with the c-plane facing upward.
Next, the high-purity hydrogen gas purified by the hydrogen purifier 22 is supplied into the reaction tube 14 while controlling the flow rate by the mass flow controller 24C to make a hydrogen gas atmosphere, and the substrate W is set to 1
Heating was performed at 100 ° C. to perform thermal etching for 10 minutes. Then, the temperature of the substrate was lowered to 520 ° C., and TMG was supplied as a Ga raw material at a flow rate of 100 μmol / min, and ammonia was supplied as a nitrogen raw material at a flow rate of 20 SLM into the reaction tube 14 to form a low-temperature buffer layer (GaN layer 28).

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masao Ikeda 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation

Claims (13)

[Claims] 1. A method for growing a p-type nitride III-V compound semiconductor using a raw material having a group III element, a raw material having a group V element and a p-type dopant in the periodic table of elements, Using a substance having a carbon atom belonging to a group IV element as a type dopant, and replacing a nitrogen atom of a group V element constituting a nitride III-V compound semiconductor with a carbon atom. A method for growing a nitride III-V compound semiconductor. 2. A raw material gas containing a Group III element,
The method according to claim 1, further comprising a step of introducing a source gas containing a group element and a source gas containing a carbon atom onto the substrate to epitaxially grow a p-type nitride III-V compound semiconductor. The method of growing a p-type nitride-based III-V compound semiconductor according to the above. 3. The method for growing a p-type nitride III-V compound semiconductor according to claim 1, wherein the source gas containing carbon atoms comprises carbon and hydrogen. 4. The method according to claim 1, wherein the source gas containing carbon atoms is C _n H _{2n + 2}
The p-type nitride-based II according to claim 3, comprising at least one substance represented by (1 ≦ n ≦ 5).
A method for growing an IV group compound semiconductor. 5. The method according to claim 1, wherein the source gas containing carbon atoms is C _n H
_4. The p-type nitride-based I according to claim 3, comprising at least one substance represented by _2n (2 ≦ n ≦ 5). 5.
A method for growing a II-V compound semiconductor. 6. The raw material gas containing carbon atoms is C _n H _2n-2.
The p-type nitride system II according to claim 3, comprising at least one kind of substance represented by (2 ≦ n ≦ 5).
A method for growing an IV group compound semiconductor. 7. A trimethylgallium gas or a triethylgallium gas as a source gas containing a Group III element,
Ammonia is used as a source gas containing a Group V element, and butane gas is used as a source gas containing carbon atoms.
GaN as a p-type nitride III-V compound semiconductor:
The method of growing a p-type nitride III-V compound semiconductor according to any one of claims 4 to 6, wherein a C crystal is grown. 8. The p-type nitride III-V compound according to claim 2, wherein the carbon-containing source gas contains an alcohol represented by ROH (R is any alkyl group). Semiconductor growth method 9. The p-type material according to claim 2, wherein the carbon-containing raw material comprises an organic compound having at least one group having a molecular weight of more than 14 bonded to a nitrogen atom.
Method for growing type nitride-based III-V compound semiconductor. 10. The organic compound is at least one amine compound selected from the group consisting of propylamine, isopropylamine, butylamine, isobutylamine, tertiarybutylamine, monomethylhydrazine, and primary amines including ethyl azide. 3. The method for growing a nitride-based III-V compound semiconductor according to claim 2, wherein: 11. The secondary amine wherein the organic compound comprises dipropylamine, diisopropylamine, dibutylamine, diisobutylamine, ditertiarybutylamine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, and secondary butylamine. 3. The method for growing a nitride III-V compound semiconductor according to claim 2, wherein the compound is at least one kind of amine compound selected from the group consisting of: 12. The organic compound is tripropylamine,
Triisopropylamine, tributylamine, triisobutylamine, tritertiarybutylamine, trisecondary butylamine, triallylamine, triethylamine,
Diisopropylmethylamine, dipropylmethylamine, dibutylmethylamine, diisobutylmethylamine,
The nitride III- according to claim 2, characterized in that it is at least one amine compound selected from the group consisting of tertiary amines including di-sec-butylmethylamine and di-tert-butylmethylamine. A method for growing a group V compound semiconductor. 13. A p-type nitride III-V compound semiconductor is grown by metal organic chemical vapor deposition or molecular beam epitaxy.
The method for growing a nitride-based III-V compound semiconductor according to any one of the above.