JP3458413B2 - Crystal growth method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal growth method for growing a crystal used in a compound semiconductor device, more specifically, a crystal used in a laser diode, a light emitting diode, a high electron mobility transistor and the like.

[0002]

2. Description of the Related Art Conventionally, it has been used for compound semiconductor devices.
The crystal growth method for the device is a semiconductor crystal substrate or
A on the epitaxial film provided on the semiconductor crystal substrate
^IIIAs_uP_1-u(A^III: In composition of 0.3 or more II
Group I atom, 0 ≤ u ≤ 1)
After carrying out growth interruption with a certain degree, C^IIIAs_zP_1-z(C
^III: Group III atom, 0 ≦ z ≦ 1) When growing a crystal,
C^IIIAs_zP_1-zIs A^IIIAs_uP_1-u(A^III:
On a group III atom with an In composition of 0.3 or more, 0 ≦ u ≦ 1)
It is directly grown.

Generally, a buffer layer grown on a semiconductor substrate is advantageously grown at a low temperature of 700 ° C. or lower in order to reduce the diffusion of impurities from the substrate crystal into the epitaxial crystal layer. Furthermore, the buffer layer is A ^III As _u
P _1-u (A ^III : Group III atom having an In composition of 0.3 or more,
When a large amount of In is contained as in 0 ≦ u ≦ 1), when grown at a high temperature, the efficiency of incorporating In into the crystal decreases, and therefore a large amount of In needs to be supplied. In terms of the raw material cost _{^{therefore, A III As u P 1-}} u (A III: In composition 0.3 or more group III atoms, 0 ≦ u ≦ 1) of the buffer layer growth, a low temperature (700 ° C. or less ) Is more advantageous.

On the other hand, the light emitting layer of an optical semiconductor device is required to have high luminous efficiency and good crystallinity. Therefore, it is generally better to grow the light emitting layer at a high temperature. Especially when the light emitting layer is made of AlGaInP or AlGaAs,
In the case of containing l, if grown at a low temperature (less than 700 ° C.), the element Al element reacts with a small amount of oxygen remaining in the growth gas, and an oxide enters the crystal as an impurity.
Fine defects may occur, and it is not possible to obtain high quality crystals with high luminous efficiency. Therefore, it is advantageous to raise the growth temperature of AlGaInP or AlGaAs (700 ° C. or higher) so that the reaction product of Al and oxygen is not mixed into the crystal.

[0005] For these ^{_{reasons, A III As u P 1-}} u when growing the growing AlGaInP or AlGaAs crystal from the crystal, A ^III As _u at a low temperature (about 660 ° C.)
P _{1- u} (A ^III : Group III atom having an In composition of 0.3 or more,
0 ≦ u ≦ 1) After growing a crystal, the temperature is raised to grow an AlGaInP or AlGaAs crystal at a high temperature of 700 ° C. or higher.

[0006]

However, when such a method is used, a part of In in the A ^III As _u P _{1 -u} crystal grown at a low temperature has a high vapor pressure and is desorbed during the temperature rise. , Surface defects occur. And Al grown on this
GaInP or AlGaAs crystals also inherit the defects. As a result, high quality AlGaInP or AlGa
There is a problem that As crystals cannot be obtained.

[0007]

[Means for Solving the Problems] Therefore, the present inventors diligently
As a result of study,^IIIAs_uP_1-uOn top
By providing a protective film with a specific composition
Prevents the accompanying crystal defects from occurring and has a good lattice match.
The present invention has been accomplished by finding a new crystal growth method. Ie book
An object of the invention is to grow A on a semiconductor crystal substrate.^IIIA
s_uP_1-u(A ^III: Group III original with In composition of 0.3 or more
, 0 ≦ u ≦ 1) AlGaI of high quality in the layer above the crystal
Can grow nP or AlGaAs crystals
The purpose of the present invention is to provide a crystal growth method.
Epi provided on conductor crystal substrate or semiconductor crystal substrate
A on the axial film^IIIAs_uP_1-uCrystal layer (A^III;
Group III atoms with an In composition of 0.3 or more, 0 ≦ u ≦ 1)
After lengthening it, B on it ^IIIAs (B^III; Al composition
After growing a thin film of group III atoms) of 0.3 or more
Then, after suspending growth, C^IIIAs_zP
_1-z(C^III; Group III atoms, 0 ≤ z ≤ 1) grow crystal layer
A crystal growth method characterized by:
The above-mentioned crystal growth method involving a heating process during a long interruption is more preferable.
A better^III, B^IIIAnd C^IIIAre Al,
Before consisting of at least one selected from Ga and In
The crystal growth method described above, more preferably, the substrate crystal is G
The above is aAs, GaP, InP, or a mixed crystal thereof.
It is achieved by the crystal growth method of.

The present invention will be described in more detail below. The A ^III As _u P _1-u (A ^III : In composition used in the present invention has a composition of 0.
A group III atom of 3 or more, 0 ≦ u ≦ 1) crystal is preferably at a temperature lower than 700 ° C., preferably 6 ° C., for the reason described above.
Grow at a temperature of about 60 ° C. B ^III As (B ^III : II having an Al composition of 0.3 or more is grown on this layer.
The thin film of the (group I atom) crystal has a lower layer of A ^III As _u P _1-u.
(A ^III : Group III atom having an In composition of 0.3 or more, 0 ≦
u ≦ 1) It can act as a protective layer that suppresses desorption of In in the crystal. The lower limit of the thickness of this layer is A
In 1As, it is 0.5 nm or more, preferably 2 nm or more. Since such is thin but effectively, the impact on the electrical and optical properties by inserting this layer is little. The upper limit of the thickness is 10 μm or less from the economical point of view, which can be made thick enough not to significantly exceed the critical film thickness at which dislocations due to lattice mismatch do not occur. B ^III A
The s (B ^III : Group III atom having an Al composition of 0.3 or more) crystal thin film is an underlayer of A ^III As _u P during its growth.
_1-u (A ^III : Group III atom having an In composition of 0.3 or more, 0
≦ u ≦ 1) The growth is performed at the same temperature as the lower layer so that a part of In is not released from the crystal and a surface defect is not generated.

B^IIIAs (B^III: Al composition is 0.3 or more
C growing on the upper group III atom)^{II I}As_zP_1-zSuccess
Length is A like AlGaInP or AlGaAs crystal
In the case of including l, the temperature up to that point for the reasons described above.
Grow at a higher temperature than. Also, C^IIIAs_zP
_1-zEven when the crystal is grown at the same temperature as the lower layer,
C^IIIAs_zP_1-zGrow for some reason before growing
In case of interruption, B ^IIIThe As protective layer is a desorption prevention layer for In.
It is extremely effective for stopping.

Each of the above-mentioned crystal growths can be carried out by utilizing a metalorganic vapor phase epitaxy (MOVPE) method or a metalorganic molecular beam epitaxy (MOMBE) method. A vapor phase epitaxy (VPE) method or a molecular beam epitaxy (MBE) method other than these may be used.

[0011]

In the crystal growth method of the present invention, C ^III As _z P
B is grown as an underlying layer before growing a _1-z crystal
^III As (B ^III : Group III atom with Al composition of 0.3 or more)
The insertion of the crystal thin film can prevent the desorption of In from the lower layer even at a high temperature. In addition, since the binding energy between Al and As is high, As is hardly desorbed, so that B ^III As (B ^III :
No defects occur on the surface of the group atom. For this reason,
A ^III A of B ^III As film surface protected by the buffer layer
Even if a C ^III As _z P _1-z crystal is grown at high temperature on a s _u P _1-u (A ^III : Group III atom having an In composition of 0.3 or more, 0 ≦ u ≦ 1) crystal, As described above, it is possible to obtain a high-quality crystal in which a growth effect at a high temperature is sufficiently exhibited without causing defects.

Further, even when the C ^III As _z P _1-z crystal is grown at the same temperature as the lower layer, the B ^III As layer is extremely effective when the growth interruption is required for some reason. In the crystal growth method described above, the substrate crystal is GaAs or G
It is suitable for the case of aP, InP, or a mixed crystal thereof, and an equivalent effect can be obtained.

[0013]

The details of the present invention will be described below with reference to the illustrated embodiments. FIG. 1 shows a first embodiment of the present invention. MOV
A Ga _0.5 In _0.5 P crystal 2 was grown as a buffer layer on the GaAs (100) substrate 1 by PE method at a thickness of 0.2 μm at 660 ° C. The growth condition at this time is a pressure of 10
² hPa, V / III ratio 450, growth rate 1.0 μm / h
It was r. And on top of this, 1.5 nm thick AlAs
The thin film 3 was grown at 660 ° C. to form a surface protective layer.
The growth conditions were a pressure of 10 ² hPa, a V / III ratio of 50, and a growth time of 7 seconds. Then the temperature up to 700 ℃ 5 ℃ /
The temperature was raised at a heating rate of min. In order to prevent the desorption of As from AlAs, 10% by volume of AH ₃ gas based on this hydrogen gas was flown in the gas atmosphere during the temperature increase in order to prevent the desorption of As from AlAs. At 700 ° C (Al _0.5 Ga _0.5 )
_0.5 In _0.5 P crystal 4 was grown to 0.5 μm. The crystal growth conditions at this time were as follows: pressure 10 ² hPa, V / III ratio 45.
The growth rate was 0 and the growth rate was 1.0 μm / hr.

[0014] COMPARATIVE EXAMPLE Moreover, except without the AlAs thin film 3 in the same manner as in Example (Al _0.5 Ga _{0. 5) 0.5}
In _0.5 P crystal was also grown. The photoluminescence intensity of the crystal provided with the AlAs layer was about 10 times that of the crystal not provided.

[0015]

As described above, according to the present invention, AlGaInP or AlGaAs crystals can be grown at a suitable temperature higher than the formation temperature of the buffer layer grown on the semiconductor substrate. Al grown in this way
The GaInP or AlGaAs crystal has few impurities and minute defects in the crystal, and thus becomes a high-quality crystal with high photoluminescence intensity.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a structure manufactured as an example of the present invention.

[Explanation of symbols]

1 (100) GaAs substrate 2 Ga _0.5 In _0.5 P crystal 3 AlAs crystal thin film 4 (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P crystal

Continuation of front page (56) Reference JP-A-57-71899 (JP, A) JP-A-61-40082 (JP, A) JP-A-64-82616 (JP, A) JP-A-1-234390 (JP , A) JP 1-28197 (JP, A) JP 2-150016 (JP, A) JP 2-168690 (JP, A) JP 2-260682 (JP, A) JP 4-268736 (JP, A) JP-A-6-271391 (JP, A) JP-A-7-82093 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C30B 1/00 -35/00 H01L 21/205 H01L 33/00 EUROPAT (QUESTEL)

Claims (4)

(57) [Claims] 1. An A ^III As _u P _1-u crystal layer (A ^III ; group III atoms having an In composition of 0.3 or more, on an epitaxial film provided on the semiconductor crystal substrate or the semiconductor crystal substrate,
0 ≤ u ≤ 1) and then B ^III As
(B ^III ; Group III atom with Al composition of 0.3 or more) After growing a crystal thin film, the growth is interrupted, and then C ^III
A method for growing an As _z P _1-z (C ^III ; group III atom, 0 ≦ z ≦ 1) crystal layer , comprising a temperature raising process during the growth interruption.
A method for growing a crystal, which comprises: 2. The crystal growth is performed in a vapor phase.
1. The crystal growth method described in 1. 3. A ^III , B ^III and C ^III are each A
The crystal growth method according to claim 1, comprising at least one selected from l, Ga, and In. 4. A substrate crystal, according to claim 1 乃 is GaAs
4. The crystal growth method according to any one of 3 to 3 .