JP3633015B2 - III-V Group Compound Mixed Crystal Growth Method - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for growing a nitrogen III-V compound mixed crystal as a group V element used for manufacturing a blue to green light emitting diode (LED) or a laser diode (LD), and in particular, a molecular beam epitaxy method at a low growth temperature. The present invention relates to a method for obtaining the mixed crystal having excellent crystallinity by a vapor phase growth method using an organic metal as a group III element source such as a metal organic vapor phase growth method (hereinafter referred to as “MOCVD method”).
[0002]
[Prior art]
Recent progress in increasing the brightness of light emitting elements such as blue to green LEDs and LDs is remarkable, and the brightness has already reached the practical level.
As materials of these light emitting elements, II-VI group systems such as ZnSSe and III-V group compound systems such as AlGaInN are used. In particular, since it has become possible to grow a p-type gallium nitride (GaN) compound having a high carrier concentration on a substrate such as sapphire or SiC with high quality, a high brightness blue LED as shown in FIG. 2 has been realized. .
Furthermore, an InGaN mixed crystal material in which the indium composition of the light emitting layer is increased is expected as a material for light emitting elements in the visible region such as green and red.
In this case, ammonia has conventionally been used as a nitrogen atom source.
[0003]
[Problems to be solved by the invention]
However, in the conventional method using ammonia as the nitrogen atom source, the V / III ratio (molar ratio) in the gas supplied to the growth apparatus becomes as high as 1000 to 10000, which imposes a burden on the equipment such as the growth apparatus and the exclusion apparatus. In order to make it small, it was necessary to keep the growth rate low (1 μm / h or less).
Furthermore, when trying to produce a light emitting layer made of, for example, an In _x Ga _1-x N mixed crystal with a large In content, there is a big problem as described below.
[0004]
If the In content is high, for example, if an In _x Ga _1-x N film or AlGaInN film having x ≧ 0.3 is to be grown, high temperature growth is performed to obtain a high quality crystal. The growth rate is greatly reduced by the separation, and conversely, when low temperature growth is performed to suppress the desorption of In, ammonia does not decompose sufficiently, resulting in the formation of nitrogen (N) atom vacancies. As a result, there is a problem that it becomes difficult to control the carrier concentration and the crystal quality is deteriorated.
[0005]
[Means for Solving the Problems]
Therefore, as a result of intensive studies aimed at solving the above problems, the present inventors have not supplied N atoms as a source gas containing only the group V of ammonia that has been conventionally used, but group III atoms and The inventors have found that the above-mentioned problems are not caused by using an organic metal containing both N atoms as a raw material, and have reached the present invention.
That is, an object of the present invention is represented by the following general formula in a method of growing a III-V group compound mixed crystal containing nitrogen as a group V element by a vapor phase growth method using an organic metal as a group III element source. This can be achieved by a method for growing a group III-V compound mixed crystal using a group III element amide compound.
[0006]
[Chemical formula 2]
M (NR ₂ ) ₃
[0007]
(In the formula, M represents a group III element , and R represents at least one functional group selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, an aryl group, an aralkyl group, a trimethylsilyl group, and a triethylsilyl group. Represents.)
[0008]
Examples of the III-V group compound mixed crystal containing nitrogen as a group V element include In _x Ga _1-x N and AlGaInN.
As the group III element compound represented by the general formula (I), M is Al, Ga, In, an amide group selected according to the group III-V mixed crystal to be grown, and —NR ₂ includes a substituent. , R is an alkyl group having 1 to 10 carbon atoms, an aryl group, an aralkyl group, a trimethylsilyl group, and a triethylsilyl group. When the number of carbons exceeds 10, the vapor pressure becomes low and it becomes difficult to supply to the MOCVD apparatus.
Preferable substituents R include CH ₃ —, C ₂ H ₅ —, C ₃ H ₇ —, C ₄ H ₉ —, C ₆ H ₅ —, CH ₃ C ₆ H ₄ —, —Si (CH ₃ ) _3. , —Si (C ₂ H ₅ ) _{3 and the} like.
[0009]
In addition, as the nitrogen source, other conventionally used compounds such as ammonia, ethyl azotide, and dimethylhumanrazine may be used in combination. When V group elements other than nitrogen, such as As and P, are included, AsH ₃ and PH ₃ can be supplied simultaneously.
A method and apparatus for growing a III-V group compound mixed crystal is not particularly limited, and a normal molecular beam epitaxy method, MOCVD method, and the like can be used.
EXAMPLES Hereinafter, although this invention is demonstrated using an Example, this invention is not limited to an Example, unless the summary is exceeded.
[0010]
【Example】
As shown in FIG. 3, the apparatus used for the growth of the present invention is provided with a substrate transfer chamber at the center and a reduced pressure MOCVD apparatus on the left and right. The growth chamber 1 is an ordinary MOCVD apparatus and is used for growing an AlGaInN-based compound semiconductor. The growth chamber 2 can radically decompose the raw material by microwave excitation, and is used for nitriding the substrate surface and growing a thin film AlGaInN-based compound. A procedure for growing an epitaxial wafer having a structure as shown in FIG. 1 will be described.
[0011]
First, a sapphire substrate is introduced into the growth chamber 2 and heated and heated. At 500 ° C., before the growth, nitrogen gas (N ₂ ) is used as a raw material, radical nitrogen is supplied to the substrate surface by microwave excitation, and oxygen (O) atoms on the surface are replaced with N atoms, that is, nitriding is performed. An In _0.4 Ga _0.6 N buffer layer of 20 nm is grown on this surface. Thereafter, the substrate is cooled, and the substrate is moved to the growth chamber 1 through the transfer chamber. The substrate is heated to 700 ° C., and an n-type In _0.4 Ga _0.6 N buffer layer 4 μm, n-type In _0.4 (Al _{0.2) is formed} on the epitaxial film growth substrate. Ga _0.8 ) _0.6 N cladding layer 1 μm, Zn-doped In _0.4 Ga _0.6 N active layer 0.1 μm, p-type In _0.4 (Al _0.2 A Ga _0.8 ) _0.6 N cladding layer of 1 μm and a p-type In _0.4 Ga _0.6 N contact layer of 1 μm are sequentially grown. At this time, hydrogen is used as the carrier gas, and tristrimethylsilylamidoindium (In (TMSA) ₃ ), tristrimethylsilylamidogallium ( Ga (TMSA) ₃ ), tristrimethylsilylamidoaluminum (Al (TMSA)) is used as the group III source gas. ₃ ) was used. Ammonia (NH ₃ ) was used as the group V source gas, but the NH ₃ / organometallic ratio was about 10 to 100, which was about 1/10 to 1/100 that of the prior art. Si or Ge was used for the n-type dopant, and Mg or Zn was used for the p-type dopant. If necessary, heat treatment is subsequently performed in the growth chamber after the growth to activate the carriers. The group III organic metal is not limited to the above organic metal, and it goes without saying that the same effect can be obtained as long as an organic metal in which an N atom is present at the group III bond. Since the stoichiometry can be easily controlled by the supply amount of NH ₃ , the conductivity type can be controlled very easily.
[0012]
An electrode was formed on the substrate surface side of the epitaxial wafer grown in this manner and processed into a chip. When this chip was assembled as a light emitting diode to emit light, a very good value was obtained with a light emission wavelength of 530 nm and a light emission output of 700 μW at a forward current of 20 mA.
Although the above embodiment has been described for the light emitting diode, it is needless to say that the semiconductor laser has the same effect.
[0013]
【The invention's effect】
By the method of the present invention, the V / III ratio could be reduced.
Furthermore, by using an organic metal having at least one N atom as a raw material for a group III (In, Al, Ga, etc.) atom bond, light emission that can cover from the ultraviolet to the red region using an AlGaInN-based material The device can be easily manufactured. In particular, the present invention is very effective in producing an AlGaInN-based LED in the visible region corresponding to green to red, which is made of an In _x Ga _1-x N mixed crystal with an increased In composition, which has been considered difficult in the past.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an example of a semiconductor device to which the present invention can be applied.
FIG. 2 is an explanatory diagram showing an example of a semiconductor device to which the present invention can be applied.
FIG. 3 is an explanatory diagram of a manufacturing apparatus used in the examples.

Claims (2)

In a method of growing a III-V group compound mixed crystal containing nitrogen as a group V element by a vapor phase growth method using an organic metal as a group III element source, a group III element amide compound represented by the following general formula I is used. A method for growing a III-V compound mixed crystal.

(Wherein, M represents a Group III element, R represents at least one functional group selected from the group consisting of C 1 -C 10 alkyl group, aryl group and aralkyl group and trimethylsilyl group and triethylsilyl group carbon Represents.) M is at least one selected from the group consisting of In, Al and Ga. III The growth method according to claim 1, wherein the growth method is a group element.

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