JPH11238685A - Crystal growing method of compound semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which a GaInNAs based compound semiconductor crystal which exhibits superior crystal characteristics can be grown safely and mass-produced. SOLUTION: A crystal growing method is a method for growing a compound semiconductor crystal represented by a formula Ga1- XInXNYAs1- Y (0<X<1, 0<Y<1) using III group materials and V group materials through vapor deposition. The crystal is grown using both the V group materials containing nitrogen and V group materials containing arsenic as the V group material. The V group material containing arsenic is an organic V group compound gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for growing a compound semiconductor crystal, and more particularly to a method for growing a GaInNAs-based compound semiconductor by vapor phase growth.

[0002]

2. Description of the Related Art When a crystal of a group III-V compound semiconductor is grown by a vapor phase growth method, a group III raw material supplying a group III element and a group V raw material supplying a group V element are used.

As an example of a group III-V compound semiconductor,
For example, a ternary GaAsN-based compound semiconductor crystal is
At the time of growth, nitrogen that supplies N element as a group V material is used.
Arsenic-containing group V raw material and arsenic-containing group V source supplying As element
Fees are used together. Conventionally, as a nitrogen-containing group V raw material
Is nitrogen (N_Two ) Gas and Reference 1 (Journal of Crystal)
 Growth 145 (1994) p.99-103)
And ammonia (NH _Three ) Activated by RF plasma
A nitrogen source was used. In addition, arsenic-containing group V raw materials
As arsine (AsH_Three ) Is commonly used
Was.

On the other hand, reference 2 (Appl. Phys. Lett. 70 (2
1), 26 May 1997, p.2861-2863) proposes to use dimethylhydrazine (DMHy) instead of ammonia as a nitrogen-containing group V raw material. Since dimethylhydrazine has a higher decomposition efficiency than ammonia, nitrogen atoms can be efficiently incorporated into a crystal when a nitride mixed crystal semiconductor is manufactured. Further, in Reference 2,
It has been proposed to use t-butylarsine (TBAs) instead of arsine as an arsenic-containing group V material. Since t-butylarsine has higher decomposition efficiency than arsine, there is an effect that the consumption of the arsenic-containing group V raw material can be reduced.

[0005] Reference 3 (Japanese Unexamined Patent Publication No. 9-283857) discloses a method of growing a quaternary GaInNAs compound semiconductor crystal as another example of a III-V compound semiconductor. . In this document 3,
Organic nitrogen compounds such as dimethylhydrazine are used as the nitrogen-containing group V raw material. As the arsenic-containing group V raw material,
Arsine is used.

[0006]

When arsine is used as an arsenic-containing group V raw material, arsine is 50% at 600 ° C.
Only decomposes. Therefore, in order to obtain a high quality compound semiconductor crystal, reference 4 (Journal of Crystal Growth 11)
5 (1991) p.1-11) It is necessary to grow the crystal at high temperature or to increase the supply of arsine.

However, GaAsN-based and GaI
When growing a compound semiconductor crystal such as an nNAs-based compound, if the growth temperature is increased, the incorporation of the N element into the crystal is suppressed. Therefore, it is necessary to increase the supply amount of the nitrogen-containing group V raw material in order to suppress the detachment of the N element from the crystal growth surface.

When the supply amount of arsine is increased, there is a concern that the reaction in the gas phase with a nitrogen-containing group V raw material such as dimethylhydrazine may affect the crystallinity.

[0009] Further, when the growth temperature is increased or when the supply amount of arsine is increased, the supply amount of the raw material gas is increased.
It is necessary to consider environmental pollution.

Further, the present inventors have paid attention to a quaternary GaInNAs-based compound semiconductor among compound semiconductor crystals. Since this GaInNAs-based compound semiconductor crystal is lattice-matched with a GaAs substrate, the Ga element, In
This is because by controlling the composition of each of the element, the N element, and the As element, a long-wavelength light-emitting element can be manufactured.

However, when growing a quaternary GaInNAs-based compound semiconductor crystal, the following three methods are used.
There is a specific problem that cannot be seen in the original GaAsN-based compound semiconductor.

That is, the present inventors have repeated experiments on the growth of a GaInNAs-based compound semiconductor crystal, and found that as the composition ratio of In element in the crystal increases, the N element hardly enters the crystal. Was. In addition,
A ternary GaInN-based compound semiconductor crystal, which has been conventionally expected to be used as a material for a blue laser device, has a similar problem. In this case, the group V element constituting the crystal is N It has been observed that it is difficult for the In element to enter the crystal because of only the element,
This is completely different from the problem of the quaternary GaInNAs-based compound semiconductor crystal.

In the growth of a quaternary GaInNAs-based compound semiconductor crystal, even if the composition ratio of the In element is increased, in order to effectively incorporate the N element into the crystal, it is necessary to use an arsenic-containing V group material. It is necessary to increase the supply ratio of the nitrogen-containing group V raw material or reduce the crystal growth temperature to suppress the elimination of the N element from the crystal growth surface.

In order to increase the supply ratio of the nitrogen-containing group V raw material, it is conceivable to increase the supply amount of the nitrogen-containing group V raw material or decrease the supply amount of the arsenic-containing group V raw material. In consideration of surface and environmental aspects, it is preferable to reduce the supply amount of the arsenic-containing group V raw material. However,
As described above, arsine as an arsenic-containing group V raw material has a low decomposition efficiency. Therefore, if the supply amount of arsine is reduced, the crystal characteristics may be degraded.

On the other hand, when the growth temperature of the crystal is lowered,
Similarly, the decomposition of arsine is hindered, and the deterioration of the crystal characteristics becomes a problem.

An object of the present invention is to solve the above-mentioned problems and to provide a method for safely growing and mass-producing a GaInNAs-based compound semiconductor crystal having excellent crystal characteristics. is there.

[0017]

Means for Solving the Problems] The present method of crystal growth compound semiconductor according to the invention, using a group III material and group V raw material, by vapor phase _{deposition, Ga 1-X In X N} Y As 1-Y
A method for growing a compound semiconductor crystal represented by (0 <X <1, 0 <Y <1), wherein a crystal growth is performed by using a nitrogen-containing group V material and an arsenic-containing group V material as a group V material. And the arsenic-containing group V raw material is an organic group V compound gas.

In this specification, the term "organic group V compound gas" refers to a compound having an organic group such as a methyl group or an ethyl group among group V compounds containing an As element.

According to the present invention, an organic group V compound gas having excellent decomposition efficiency is used as an arsenic-containing group V raw material during crystal growth of a GaInNAs-based compound semiconductor. For this reason, a crystal having good characteristics can be grown with a small amount of raw material supply as compared with the case of using arsine which has been frequently used in the past.

As the organic group V compound gas, specifically,
Examples include t-butylarsine (TBAs) or trimethylarsenic (TMAs). These t-butylarsine and trimethylarsenic are both liquid substances at room temperature and are usually stored in a stainless steel (SUS) container, but should be bubbled with a so-called carrier gas such as hydrogen (H ₂ ) gas. Thereby, it can be transported as a source gas for growing a semiconductor crystal.

In the present invention, examples of the nitrogen-containing group V raw material include monomethylhydrazine (MMH).
y) or dimethylhydrazine (DMHy). Since they are excellent in decomposition efficiency, crystals having good characteristics can be grown with a small amount of raw material supplied.

In the present invention, preferably, the molar supply ratio between the arsenic-containing group V material and the group III material is 1 <
The ratio is preferably [arsenic-containing group V raw material] / [group III raw material].

[Arsenic-Containing Group V Raw Material] / [Group III Raw Material]
If the molar supply ratio of the raw material represented by the formula is 1 or less, the characteristics of the crystal deteriorate.

On the other hand, when the raw material molar supply ratio is larger than 1, crystals having good characteristics can be grown in any case. Conventionally, when arsine was used, the raw material molar supply ratio had to be increased to about 16, but according to the present invention, the supply amount of the arsenic-containing group V raw material was reduced by using an organic group V compound gas. It is possible to reduce it. However, if the raw material molar supply ratio is larger than 10, the nitrogen-containing V
Since it is necessary to supply a large amount of group material, the properties of the crystal may be deteriorated. Therefore, in the present invention, the molar supply ratio of the arsenic-containing group V raw material to the group III raw material is more than 1 and more preferably 10 or less.

Further, in the present invention, the growth temperature is set at 500 ° C. to 600 ° C. during the vapor phase growth of the compound semiconductor crystal.
It is preferably set to ° C.

[0026]

FIG. 1 is a sectional view showing the structure of an example of a vapor phase growth apparatus for carrying out a compound semiconductor crystal growth method according to the present invention.

Although a horizontal reactor is shown in this example, the present invention can be practiced using a vertical reactor.

Referring to FIG. 1, the vapor phase growth apparatus comprises a stainless steel (SUS) chamber 1 for performing vapor phase growth,
The apparatus includes a quartz flow channel 2 for supplying a source gas and an exhaust pipe 3. In the chamber 1 made of stainless steel, a carbon susceptor 5 coated with SiC for heating the substrate 4 is provided. A rotating device 51 for rotating the substrate 4 during vapor phase growth is attached to a lower portion of the carbon susceptor 5. At the center of the rotating device 51, a thermocouple 6 for measuring the temperature of the substrate 4 is attached.

Using the thus-configured vapor phase growth apparatus, according to the present invention, crystal growth of a GaInNAs-based compound semiconductor is performed as follows.

First, the substrate 4 is placed on the carbon susceptor 5 provided in the stainless steel chamber 1. As the substrate 4, G is used to promote epitaxial growth.
Although an aAs substrate is preferable, a Ge substrate, a Si substrate, or the like can also be used.

Next, the substrate 4 is heated to a predetermined temperature by energizing and heating the carbon susceptor 5.

Subsequently, a carrier gas and a raw material gas are introduced into the stainless steel chamber 1 through the quartz flow channel 2.

Examples of the carrier gas include hydrogen (H ₂ ) gas highly purified by a hydrogen purifier, nitrogen (N ₂ ) gas highly purified by a purifier, and helium (He).
Gas or the like is used. Nitrogen (N ₂ ) as carrier gas
When a gas is used, the efficiency of taking in the N element in the crystal is improved.

As the raw material gas, a p-type or n-type dopant raw material gas is used, if necessary, in addition to the group III raw material and the group V raw material. Group V raw materials include t-butylarsine (TBAs), trimethylarsenic (TMA)
An arsenic-containing group V raw material composed of an organic group V compound gas such as s) and a nitrogen-containing group V raw material such as monomethylhydrazine (MMHy) and dimethylhydrazine (DMHy) are used. Group III raw materials include triethylgallium (TE
G), trimethylindium (TMI) or the like is used.

The pressure in the stainless steel chamber 1 during vapor phase growth may be reduced pressure or normal pressure. The exhaust gas after the reaction is exhausted to the outside of the stainless steel chamber 1 by the exhaust pipe 3.

[0036]

Embodiment 1 Using the vapor phase growth apparatus shown in FIG. 1, Ga _1-x In _x N _y As _{1 -y} (0 <
A compound semiconductor crystal represented by X <1, 0 <Y <1) was grown.

As the substrate, GaAs was used, and the pressure in the stainless steel chamber 1 was reduced to 1/10 atm. Here, triethyl gallium (TE) is selected so that the concentration of the indium (In) element in the crystal becomes X = 0.1.
G) and a fixed amount of trimethylindium (TMI) were supplied. Hydrogen (H ₂ ) was used as a carrier gas.

[TBAs] / ([TEG] + [TM
When the molar supply ratio of the arsenic-containing group V raw material and the group III raw material represented by I]) was set to 1, a broad X-ray diffraction peak having a half width of 250 arcsec indicating deterioration in crystallinity was observed. However, [TBAs] / ([TE
G] + [TMI]) and the arsenic-containing group V raw material and I
When the molar supply ratio with the Group II raw material was set to be larger than 1,
It was found that the half width was sharply improved.

Next, the growth temperature was set to 550 ° C., and [TBA
s] / ([TEG] + [TMI]), the molar supply ratio between the arsenic-containing group V material and the group III material is 1.8, and represented by [DMHy] / ([DMHy] + [TBAs]). By setting the molar supply ratio of the nitrogen-containing group V source to the entire group V source to be 0.98, a GaInNAs-based compound semiconductor crystal was grown to 0.5 μm.

FIG. 2 shows the GaIn thus obtained.
FIG. 3 is a diagram showing a rocking curve of an NAs-based compound semiconductor crystal measured by X-ray diffraction. In FIG. 2, the horizontal axis is Δ2
θ (deg.), and the vertical axis indicates the X-ray diffraction intensity (a.
u. ).

Referring to FIG. 2, Ga _0.9 In _0.1 NAs
The peak half width of the compound semiconductor crystal was 30 arcsec, and it was found that good crystallinity was obtained.

[TBAs] / ([TEG] + [T
MI]), the optical characteristics of the crystals were observed by changing the molar supply ratio between the arsenic-containing group V raw material and the group III raw material, and the molar supply ratio between the arsenic-containing group V raw material and the group III raw material was less than 1. It was found that the half-width of the photoluminescence (PL) spectrum became smaller as the size became larger. However, [TBAs] / ([TEG] + [T
MI]), when the molar supply ratio of the arsenic-containing group V raw material to the group III raw material was larger than 10, no change was observed in the optical characteristics.

Next, [DMHy] / ([DMHy] +
The change in the nitrogen (N ₂ ) concentration in the obtained crystal was observed by changing the molar supply ratio of the nitrogen-containing group V raw material to the whole group V raw material represented by [TMAs]).

FIG. 3 shows the result. In FIG. 3, the horizontal axis represents the molar supply ratio of the nitrogen-containing group V raw material to the entire group V raw material, and the vertical axis represents the nitrogen concentration (%). The nitrogen concentration (%) is determined by SIMS (Secondary Io
n Mass Spectroscopy: secondary ion mass spectrometry).

Referring to FIG. 3, by changing the molar supply ratio of the nitrogen-containing group V raw material to the entire group V raw material,
It can be seen that it is possible to grow a GaInNAs-based compound semiconductor crystal while freely controlling the nitrogen concentration.

(Example 2) GaAs was used as the substrate, and the pressure in the stainless steel chamber 1 was reduced to 1/10 atm, and Ga _{1 -X} In _X N _Y As _{1 -Y} (0 <X
A compound semiconductor crystal represented by <1,0 <Y <1) was grown.

Here, constant amounts of triethylgallium (TEG) and trimethylindium (TMI) were supplied so that the concentration of the indium (In) element in the crystal became X = 0.15. Hydrogen (H ₂ ) as a carrier gas
Was used. The growth temperature was set to 530 ° C and [TBAss] /
([TEG] + [TMI]), the molar feed ratio of the arsenic-containing group V raw material to the group III raw material is set to 2, and [DMH
y] / ([DMHy] + [TBAs])
Assuming that the molar supply ratio of the nitrogen-containing group V source to the entire group V source is 0.965, G substantially lattice-matched to the GaAs substrate
was grown compound semiconductor crystal represented by _{a 0.85 In 0.15 N 0. 05 As} 0.95.

FIG. 4 is a diagram showing the result of photoluminescence (PL) measurement of the obtained crystal at room temperature. FIG.
In the graph, the horizontal axis represents the wavelength (nm), and the vertical axis represents the PL emission intensity (au).

Referring to FIG. 4, at a wavelength of approximately 1.3 μm
Could be confirmed. Next, nitrogen as carrier gas
(N_Two )), The incorporation efficiency of N element into the crystal becomes
Utilizing the improvement, raise the growth temperature to 600 ° C.
Nitrogen (N_Two To grow using
Was. As a result, [TBAs] / ([TEG] + [TM
I]) an arsenic-containing group V raw material and a group III raw material
When the molar supply ratio of
Combined Ga_0.85In_0.15N_0.05As _0.95Compound semiconductor
Crystals could be grown. [DMHy] /
Group V raw material represented by ([DMHy] + [TBAs])
The molar feed ratio of the nitrogen-containing group V raw material to the whole is 0.9
It was 8.

Embodiment 3 Next, using trimethylarsenic (TMAs) as an arsenic-containing group V raw material, Ga _{1- X} In
_X N _Y As _1-Y was grown compound semiconductor crystal represented by (0 <X <1,0 <Y <1).

First, fixed amounts of triethylgallium (TEG) and trimethylindium (TMI) were supplied so that the concentration of the indium (In) element in the crystal became X = 0.1. Also, [TMAs] / ([TEG] +
[DMHy] / ([DMI], the molar supply ratio of the arsenic-containing group V raw material and the group III raw material represented by [TMI]) is set to 2.
Hy] + [TMAs]), the molar supply ratio of the nitrogen-containing group V source to the entire group V source was 0.98, and the growth temperature was 550 ° C. The pressure in the stainless steel chamber 1 was reduced to 1/10 atm.

The mixed crystal ratio of the crystals thus obtained is
Ga _0.9 In _0.1 N _0.03 As _{0.97 was obtained} , and light emission at 1.2 μm was confirmed.

Embodiment 4 In general, in a GaInNAs-based compound semiconductor crystal, a crystal having excellent optical characteristics is easily obtained as the concentration of the N element in the crystal is lower. So N
A long wavelength light emitting device was manufactured by growing a GaInNAs-based compound semiconductor crystal by increasing the concentration of the In element instead of decreasing the concentration of the element.

First, fixed amounts of triethylgallium (TEG) and trimethylindium (TMI) were supplied so that the concentration of the indium (In) element in the crystal became X = 0.3. Hydrogen (H ₂ ) was used as a carrier gas. When the indium (In) mixed crystal ratio in the crystal is large, since the N element is hardly taken in, the growth temperature is set to 500 ° C. in order to increase the adsorption rate of the N element on the crystal growth surface.
[DMHy] / ([DMHy] + [TBAs])
The molar supply ratio of the nitrogen-containing group V raw material to the entire group V raw material represented by is 0.985. [TBAs]
Arsenic-containing V represented by / ([TEG] + [TMI])
The molar supply ratio between the group III raw material and the group III raw material was set to 2, and the pressure in the stainless steel chamber 1 was set to 1/10 atm.

Thus, a quantum well structure as shown in FIG. 5 was formed. First, an n-type GaAs buffer layer having a thickness of 0.3 μm is grown on an n-type GaAs substrate at a growth temperature of 600 ° C., and then an n-type Al _0.4 Ga film having a thickness of 1.5 μm is formed.
_{A 0.6} As barrier layer was grown. At this time, tetraethylsilane (TeESi) was used as an n-type dopant material. Subsequently, undoped GaAs having a thickness of 0.15 μm
During the growth of the spacer layer, the growth temperature was lowered to 500 ° C., and as a well layer, a 60 ° -thick Ga _0.7 In _0.3 N _0.01 As _0.99
Was grown. Further, during the growth of the undoped GaAs spacer layer having a thickness of 0.15 μm, the growth temperature was increased to 600 ° C.
A type Al _0.4 Ga _0.6 As barrier layer and a p-type GaAs contact layer having a thickness of 0.2 μm were grown. Diethyl zinc (DEZn) was used as a p-type dopant material.

In the thus obtained semiconductor multilayer film having a quantum well structure, a p-type electrode is formed on the p-type GaAs contact layer and an n-type electrode is formed on the back surface of the n-type GaAs substrate. Was prepared. In this long-wavelength light-emitting device, the GaInNAs-based compound semiconductor crystal constituting the well layer has distortion without lattice matching with the substrate. However, since the thickness of the well layer is equal to or less than the critical thickness, a crystal having few dislocations can be grown, and a long-wavelength light emitting device can be manufactured.

It should be understood that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0058]

As described above, according to the present invention, when growing a GaInNAs-based compound semiconductor, a conventional arsine (AsH ₃ ) is used by using an organic V-group compound gas as an arsenic-containing V-group source material. As compared with the conventional case, good crystal growth can be achieved with a lower arsenic-containing group V source material supply ratio. Therefore, reduction of toxic arsenic (As) -containing waste can be expected, which is also effective in preventing environmental pollution.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the configuration of an example of a vapor phase growth apparatus for performing a compound semiconductor crystal growth method according to the present invention.

FIG. 2 is a diagram showing a rocking curve of the Ga _0.9 In _0.1 NAs compound semiconductor crystal obtained in Example 1 by X-ray diffraction measurement.

FIG. 3 is a diagram showing a change in nitrogen concentration in a GaInNAs-based compound semiconductor crystal when a molar supply ratio of a nitrogen-containing group V source to the entire group V source is changed.

FIG. 4 is a diagram showing a result of a PL measurement at room temperature of a Ga _0.85 In _0.15 NAS compound semiconductor crystal obtained in Example 2.

FIG. 5 is a cross-sectional view illustrating a configuration of a quantum well structure obtained in Example 4.

[Explanation of symbols]

 Reference Signs List 1 chamber made of stainless steel 2 flow channel made of quartz 3 exhaust pipe 4 substrate 5 carbon susceptor 6 thermocouple 51 rotating device

Claims (4)

[Claims] 1. A group III source and a group V source, Ga _{1 -X} In _X N _Y As _{1 -Y} (0 <X
A method for growing a compound semiconductor crystal represented by <1,0 <Y <1), wherein a crystal growth is performed using a nitrogen-containing group V material and an arsenic-containing group V material as the group V material. Wherein the arsenic-containing group V raw material is an organic group V compound gas;
A method for growing a compound semiconductor crystal. 2. The method of growing a compound semiconductor crystal according to claim 1, wherein said arsenic-containing group V material includes at least one material selected from the group consisting of t-butylarsine and trimethylarsenic. 3. The method of growing a compound semiconductor crystal according to claim 1, wherein the nitrogen-containing group V source contains at least one source selected from the group consisting of monomethylhydrazine and dimethylhydrazine. 4. The molar supply ratio of the arsenic-containing group V raw material to the group III raw material is 1 <[arsenic-containing group V raw material] / [I
The compound semiconductor crystal growth method according to any one of claims 1 to 3, wherein the compound semiconductor material is a group II raw material.