JPH1168235A - Crystal growth method of algaas compound semiconductor and manufacture of semiconductor laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To grow an AlGaAs film wherein impurities such as oxygen and water are little without decreasing crystal growth temperature, by setting the growth temperature of compound semiconductor in a specified range, and setting the ratio of group V material gas amount to group III material gas amount to be at least a specified value. SOLUTION: A buffer layer 2, a clad layer 3, an undoped active layer 4, a P-type first clad layer 5, and an N-type block layer 6 are formed in order on a substrate 1. A P-type second clad layer 8, and a P-type contact layer 9 are formed on the block layer 6. After that, an N electrode 10 is formed on the lower surface, and a P electrode 11 is formed on the upper surface. For the P-type clad layers 5, 8, the condition at the time of crystal growth of compound semiconductor whose carrier concentration is at most 1×10<17> /cm<3> is set as follows; the growth temperature is higher than or equal to 750 deg.C and lower than or equal to 850 deg.C and, the ratio V/III of group V material gas amount to group III material gas amount is at least 150. Thereby crystals having low carrier concentrations in both an N-type and a P-type can be obtained with high quality and excellent reproducibility.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor laser, L
AlGa used for manufacturing ED, HBT, HEMT, etc.
The present invention relates to a method for growing a crystal of an As compound semiconductor and a method for manufacturing a semiconductor laser using the same.

[0002]

2. Description of the Related Art Semiconductor lasers, LEDs, HBTs, HEMs
As a crystal growth method of an AlGaAs compound semiconductor used for T or the like, a metal-organic vapor phase epitaxy (MOCVD) method is expected to be most promising because it has excellent mass productivity and can grow an ultra-thin film crystal. .

[0003] In the MOCVD method, when a p-type or n-type growth layer of an AlGaAs compound semiconductor is grown, Al and Ga raw material compounds, As raw material compounds, p-type impurity raw materials or n-type impurity raw materials are supplied onto a substrate to crystallize. Do the growth.

Specifically, when an n-type AlGaAs layer is grown, silane (S
iH ₄ ) or disilane (Si ₂ H ₆ ), triethylgallium (TEGa) or trimethylgallium (TMGa) as a Ga source compound, triethylaluminum (TEAl) or trimethylaluminum (TMAl) as an Al source compound, and arsine (AsAl) as an As source compound. As
H _3), tertiary butyl arsine (TBA), with a carrier gas such as hydrogen (H ₂₎ is supplied onto the substrate n
A type AlGaAs crystal is grown.

When a p-type AlGaAs layer is grown, diethyl zinc (DE) is used as a p-type impurity material compound.
Zn), dimethyl zinc (DMZn), cyclopentadienyl magnesium (Cp ₂ Mg), diethyl beryllium (DEBe), triethylgallium (TEGa) or trimethylgallium (TMGa) as an Al raw material compound and a Ga raw material compound, an Al raw material Triethylaluminum (TEAl) or trimethylaluminum (TMAl) as a compound, arsine (AsH ₃ ), tertiary butylarsine (TB
A) Hydrogen (H ₂ ) or the like is supplied as a carrier gas onto a substrate to grow a p-type AlGaAs crystal.

[0006] In controlling the amount of addition of a predetermined impurity in crystal growth of a p-type or n-type growth layer, MOC is usually used.
In the VD method, control is performed by changing the supply amount of impurity gas using an MFC (mass flow controller) or the like. The temperature for crystal growth is usually 750 ° C.

[0007]

However, in the MOCVD method, since an organic metal compound is used as a raw material compound, carbon is taken in the growth layer. In the growth by MOCVD, carbon usually exists at the atomic position of As in an AlGaAs crystal and functions as a p-type impurity (acceptor). AlG
The mechanism of carbon incorporation during aAs growth differs depending on the temperature during crystal growth.
This is because carbon is taken in due to the decomposition of the l and Ga raw materials, and in high-temperature growth, the decomposed carbon of the organometallic compound is taken into As vacancies on the AlGaAs surface.

[0008] Explaining the dependence of the concentration of incorporated carbon on the growth temperature, an effective group V material for capturing carbon due to undecomposed Al and Ga materials and decomposing As material as the crystal growth temperature decreases. The carbon concentration tends to increase due to a decrease in the ratio between the supply amount of the compound and the supply amount of the group III source gas (hereinafter, referred to as V / III). On the other hand, as the crystal growth temperature increases, the number of As vacancies on the AlGaAs surface increases, so that the carbon concentration tends to increase again. Therefore, there were suitable growth temperature conditions (600 ° C. to 750 ° C.) to minimize the carbon concentration.

According to the study of the present inventors, AlG
It was found that as the mixed crystal ratio of Al in the aAs crystal increased, the rate of incorporation of carbon increased. Therefore, even in the production of an undoped crystal without doping impurities,
As the mixed crystal ratio of Al increases, the AlGaAs crystal tends to be p-type.

FIG. 1 shows a growth temperature of 750 ° C. using the MOCVD growth method, V / III = 120, and undoped Al _x.
4 shows the dependence of the p-type carrier concentration of Ga _1-x As on the mixed crystal ratio. When the mixed crystal ratio of Al is 0.5 or more, even undoped 1 ×
It can be seen that a p-type carrier concentration of 10 ¹⁷ / cm ³ or more is exhibited.

FIG. 2 shows undoped A at a growth temperature of 750 ° C.
The V / III dependence of the p-type carrier concentration in a growth film grown by MOCVD of l _0.6 Ga _0.4 As is shown. When V / III ≦ 150, 2 × 10 ¹⁷ even if undoped
It can be seen that a p-type carrier concentration of / cm ³ or more is exhibited.

Usually, in an AlGaAs compound semiconductor device such as a semiconductor laser, particularly in a light emitting device, A
It has n-type and p-type cladding layers having a mixed crystal ratio of 0.5 or more, and particularly in the case of a laser, when the carrier concentration of the cladding layer is high, the resistance of the cladding layer decreases and the spread of injection current increases. A problem arises that the operating current increases due to the increase. Therefore, it is necessary to lower the carrier concentration of the p-type cladding layer for an n-type substrate and the n-type cladding layer for a p-type substrate.

At present, ordinary MOCVD crystal growth is generally performed at a growth temperature of 750 ° C. or less and V / III = 120 or less. However, the mixed crystal ratio of Al is 0.1.
The incorporation of carbon is 5 or more, the growing crystal is to indicate 1 × 10 ¹⁷ / cm ³ or more p-type in the undoped, the amount of dopant for compensating must be added in 10 ¹⁷ the order, 1 × 10 ¹⁷ / n having a carrier concentration of not more than cm ³
It is difficult to form a growth layer with good control and reproducibility for both the mold and the p-type. Although the amount of carbon mixed into AlGaAs can be reduced by lowering the growth temperature,
When the growth temperature is lowered, the amount of impurities other than carbon, such as oxygen and water, which deteriorate the film quality of the grown crystal film increases, and the crystallinity of the grown layer also deteriorates. Oxygen is easily bonded to aluminum, and the amount of oxygen mixed into the crystal growth film increases with an increase in the Al mixed crystal ratio of AlGaAs.

According to the present invention, an AlGaAs growth film containing a small amount of impurities such as oxygen and water is grown without lowering the crystal growth temperature, and an AlGaAs film having a low carrier concentration is formed.
The purpose is to obtain a GaAs growth film.

[0015]

According to the present invention, Al _x Ga _{1 -x} A of the present invention is used.
In the method for growing a crystal of an s (x ≧ 0.5) compound semiconductor, the growth temperature is 750 ° C. or more and 850 ° C., and the ratio V / III between the group V source gas amount and the group III source gas amount is 150 or more. It is characterized by.

The Al _x Ga _{1 -x} As (x ≧ 0.
5) The compound semiconductor is n-type, and Si is used as an n-type dopant.

The Al _x Ga _{1 -x} As (x ≧ 0.
5) The compound semiconductor is p-type, and a group II raw material is used as a p-type dopant.

The method of manufacturing a semiconductor laser according to the present invention is characterized in that an Al _x Ga _{1 -x} As (x ≧ 0.5) compound semiconductor having a carrier concentration of 1 × 10 ¹⁷ / cm ³ or less is grown as a p-type cladding layer. Is that the growth temperature is 750 ° C. or more and 850 ° C.
° C, and the ratio V / III between the amount of the group V source gas and the amount of the group III source gas is 150 or more.

In the present invention, the growth temperature is set to 750 ° C. to 850 ° C. in order to reduce As vacancies accompanying the increase in the growth temperature.
By setting V / III to 150 or more, an undoped film having a carrier concentration of 1 × 10 ¹⁷ / cm ³ or less was obtained. Under the above-mentioned growth conditions, n-type is doped with Si and p-type is doped with Be, Mg, and Zn.
Al _x G having a carrier concentration of 5 × 10 ¹⁷ / cm ³ or less
An a _1-x As (x ≧ 0.5) crystal could be produced with good control and good reproducibility.

The present inventors have proposed that Al _x Ga _{1 -x} As (x ≧
0.5) In order to reduce the oxygen concentration in the grown film,
Oxygen was intentionally mixed (usually less than 100 ppm
It was set to 0 ppm. ) As a result of crystal growth using trimethylaluminum, a growth temperature of 750 ° C. or higher and V
By setting the / III ratio to 150 or more, the oxygen concentration in the grown film can be reduced below the measurement limit of secondary ion mass spectrometry (2 ×
10 ¹⁶ / cm ³ ). However, when the growth temperature exceeded 850 ° C., the morphology of the grown film surface deteriorated.

In addition, Si as an n-type dopant is Al
N-type when it enters the atomic position of Al or Ga in GaAs,
Although it is an amphoteric impurity showing p-type when it enters the atomic position of As, the amount of Si entering the atomic position of As decreases by reducing the vacancies of As, and the amount of carriers used for compensation decreases. And thus the efficiency of Si doping increases. Also, Be, Mg, Zn which are p-type dopants are used.
Is located at the Al or Ga atomic position of AlGaAs.
As for the p-type dopant, as the coverage of As increases, the re-evaporation of Be, Mg, and Zn decreases, and the doping efficiency of Group II increases.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION

(Example 1) n-type Ga was deposited on n-type GaAs by MOCVD.
An As grown film is grown, and a low concentration n-type Al _0.6
For growing Ga _0.4 As, trimethylgallium (TM
Ga), trimethylaluminum (TMAl), arsine (AsH ₃ ) diluted to 10% with H ₂ , and silane (Si)
H ₄ , 10 ppm) and hydrogen (H ₂ ) were used as raw materials. More specifically, a reduced-pressure horizontal high-frequency heating furnace was used as a vapor phase growth apparatus, the furnace pressure was stabilized at 76 Torr, the substrate temperature was stabilized at 750 ° C., and the trimethylgallium flow rate was 1.
8 × 10 ⁻⁵ mol / min, arsine flow rate 3.6 × 10
^-3 mol / min, silane flow rate 4.5 × 10 ^-7 mol /
min, flow rate sum of raw material gas and carrier gas 9 l / min
Under these conditions, the film thickness is 0.5 μm
Was grown.

Thereafter, the trimethylgallium flow rate was 7.4 × 10 ⁻⁶ mol / min, while the arsine flow rate was unchanged.
Trimethylaluminum flow rate 1.06 × 10 ⁻⁵ mol /
min (V / III = 200), silane flow rate 2.0 × 1
N-type Al _0.6 Ga _0.4 having a thickness of 5.0 μm at 0 ^-7 mol / min, a flow rate of a source gas and a carrier gas of 9 l / min.
An As thin film was grown. When the carrier concentration of the obtained Al _0.6 Ga _0.4 As film was measured, it was 7.0 × 10 ^{16 for the} n-type.
/ Cm ³ .

To check the reproducibility of growth, 5 runs were performed under the same conditions as above. The resulting membranes were all 6.0-6.0
An n-type of 8.0 × 10 ¹⁶ / cm ³ is shown, indicating that the reproducibility of film growth is good.

On the other hand, an arsine flow rate of 1.08
× 10 ⁻³ mol / min (V / III = 60), silane flow rate 5.8 × 10 ⁻⁷ mol / min, growth temperature 700 ° C.
When the growth film was grown for 5 run,
An n-type of 9.0 × 10 ^{15 to} 1.0 × 10 ¹⁷ cm ³ was shown.

When the obtained growth film was subjected to SIMS measurement, the growth film obtained under the growth conditions of V / III = 200 and a growth temperature of 750 ° C. had a density of 2 × 10 ¹⁶ / cm ³ (measurement limit). The oxygen concentration was shown, but at V / III = 60 and a growth temperature of 700 ° C., the oxygen concentration was 4 × 10 ¹⁶ / cm ³ . By growing under the conditions according to the present invention, a high-quality, low-concentration n-type grown film with few impurities was obtained with good reproducibility.

The growth was carried out by changing the dopant material from silane to disilane. By growing under the conditions of the present invention, an n-type growth film of 1.5 × 10 ¹⁷ / cm ³ or less was obtained with good reproducibility. I got it.

(Embodiment 2) p-type GaAs on n-type GaAs
An s film is grown, and a low concentration p-type Al is formed on the p-type GaAs film.
To grow _0.52 Ga _0.48 As, trimethyl gallium (TMGa), trimethyl aluminum (TMAl), arsine (AsH ₃ ) diluted to 10% with H ₂ , diethyl zinc (DEZn), and hydrogen (H ₂ ) are used as raw materials. used.

More specifically, a low-pressure horizontal high-frequency heating furnace is used as a vapor phase growth apparatus, and the furnace pressure is 76 Torr.
r, after the substrate temperature was stabilized at 750 ° C., the trimethylgallium flow rate was 1.8 × 10 ⁻⁵ mol / min, and the arsine flow rate was 3.6 × 10 ⁻³ mol / min (V / III = 20).
0), diethyl zinc flow rate 9.2 × 10 ⁻⁷ mol / mi
n, at a flow rate sum of the source gas and the carrier gas of 9 l / min,
While maintaining these conditions constant, a 0.5 μm-thick p
Type GaAs thin film is grown, and then trimethylgallium flow rate is 8.46 × 10 ⁻⁶ mol / min, trimethylaluminum flow rate is 9.36 × 10 ⁻⁶ mol / min, diethyl zinc flow rate is 9.2 × 10 ⁻⁷ mol / min, At a flow rate sum of the source gas and the carrier gas of 9 l / min, the film thickness is 0.5 μm.
An m-type Al _0.52 Ga _0.48 As thin film was grown. When the carrier concentration of the obtained film was measured, the p-type was 8.5 ×
A carrier concentration of 10 ¹⁶ cm ³ was shown. 5 run was performed under the same conditions as above to see the reproducibility of growth. All of the obtained Al _0.52 Ga _0.48 As films were 7.0 to 9.5 ×
It shows a p-type of 10 ¹⁶ / cm ³ , indicating that the reproducibility of the grown film is good.

On the other hand, an arsine flow rate of 1.08
When growth was performed at × 10 ⁻³ mol / min (V / III = 60), a flow rate of diethyl zinc of 7.5 × 10 ⁻⁷ mol / min, and a growth temperature of 750 ° C., the obtained growth film was:
It showed a p-type of 1.0 × 10 ¹⁷ / cm ³ . SIMS measurement of the obtained grown film showed that the atomic concentration of Zn was 5.0 × 10 ¹⁶ / cm ³ or less and the carbon concentration was 1.0 × 10 ¹⁷ / cm ³ . . In order to see reproducibility even in a growth film forming method using a conventional method, when 5 run growth was performed, 1.0 × 10 ^{17 to} 3.0 × 10 ^{17 was obtained.}
/ Cm ³ becomes a p-type film having a carrier concentration of 1.0 × 10 3
^A p-type growth film having a carrier concentration of ¹⁷ / cm ³ or less could not be obtained.

In the SIMS measurement, V / III
= 200, the growth film obtained under the growth condition of the growth temperature of 750 ° C. showed an oxygen concentration of 2 × 10 ¹⁶ / cm ³ (measurement limit). By growing under the conditions of the present invention, a high-quality, low-concentration n-type Al _0.52 Ga _0.48 As film with few impurities was obtained with good reproducibility.

Even if the dopant is changed from diethyl zinc to dimethyl zinc, cyclopentadienyl magnesium, diethyl beryllium, the p-type growth of 1.5 × 10 ¹⁷ / cm ³ or less can be achieved by growing under the conditions of the present invention. The film was obtained with good reproducibility.

(Embodiment 3) FIG. 3 is a sectional view of a semiconductor laser of Embodiment 3. This is a structure called a self-aligned type, in which an n-type GaAs buffer layer 2 (1.5 × 10 ¹⁸ / cm ³ , a thickness of 1.5 × 10 ¹⁸ / cm ³ ) is formed on an n-type GaAs substrate 1 (carrier concentration 2 × 10 ¹⁸ / cm ³ ) by MOCVD. 0.5 μm setting),
Si-doped n-type Al _0.5 Ga _0.5 As clad layer 3 (carrier concentration 4 × 10 ¹⁷ / cm ³ , thickness 1 μm), undoped Al _0.14 Ga _0.86 As active layer 4 (thickness 0.04 μ)
m), Zn-doped p-type Al _0.5 Ga _0.5 As first cladding layer 5 (carrier concentration 1 × 10 ¹⁷ / cm ³ , thickness 0.3 μm)
m setting), Si-doped n-type AlGaAs block layer 6
(Carrier concentration: 3 × 10 ¹⁸ / cm ³ , thickness: 0.8 μm). The n-type AlGaAs block layer 6 has a thickness of 4 μm.
The current paths 20 are formed by removing the stripes having a width of m. Furthermore, Zn-doped p-type Al _0.5 Ga _0.5
As second cladding layer 8 (1.5 × 10 ¹⁸ / cm ³ , thickness 1 μm), Zn-doped p-type GaAs contact layer 9
(4 × 10 ¹⁸ / cm ³ , thickness 1 μm).
Then, after forming an n-electrode 10 on the lower surface and a p-electrode 11 on the upper surface, the bar is divided into bars, the light emission on both sides of the bar is coated with a reflective film, and further divided into chips to form individual elements. Thus, a semiconductor laser having a wavelength of 780 nm and an output of 5 mW is obtained. Here, the group III material is TMG (trimethylgallium), TMA (trimethylaluminum), the group V material is AsH ₃ (arsine), the n-type dopant material is SiH ₄ (silane), and the p-type dopant material is D.
EZ (diethyl zinc) was used. Growth temperature is 750
C., the growth pressure is 76 Torr, and V / III = 400.

For comparison, a growth temperature of 750 ° C. and V / II
I = 60 (In order to make the carrier concentration the same as much as possible, the p-type Al _0.5 Ga _0.5 As first cladding layer 5 has a DEZ
Without doping, Zn is doped only in the p-type Al _0.5 Ga _0.5 As second cladding layer 8. ), A semiconductor laser having the same structure as above was manufactured. In order to investigate the doping concentration in the stripe, a sample having a width of 1000 μm was prepared.

The doping concentration was measured by SIMS analysis. FIG. 4 shows the profiles of Zn and Si of SIMS grown at a growth temperature of 750 ° C. and V / III = 400.
The Zn concentration of the low-concentration Zn-doped first cladding layer 5 is increased by the diffusion of Zn from the high-concentration Zn-doped second cladding layer. This phenomenon is caused by the growth temperature of 750 ° C and V / I
The sample grown at II = 60 had almost the same profile, and there was no significant difference under the growth conditions.

Next, in order to check the doping concentration outside the stripe, in the above process, the Si-doped n-type AlGaAs was used.
A sample having grown up to the s block layer 6 was prepared. FIG.
6 shows the SI of the sample for measuring the doping concentration outside the stripe.
3 shows MS measurement results. FIG. 5 shows a growth temperature of 750 ° C. and V / I
II = 400, Zn-doped p-type A
The carrier concentration of the l _0.5 Ga _0.5 As first cladding layer 5 was 1 × 10 ¹⁷ / cm ³ as set. FIG. 6 is a profile of a sample grown at a growth temperature of 750 ° C. and V / III = 60. The carrier concentration of the Zn-doped p-type Al _0.5 Ga _0.5 As first cladding layer 5 is 2.5 × 10 ¹⁷ / cm ³ . Indicated.

When the operating current of the semiconductor laser fabricated under these two conditions was measured, the growth temperature was 750.degree.
= 38 mA for a semiconductor laser grown at = 400, a growth temperature of 750 ° C., and an operating current of a semiconductor laser grown at V / III = 60 of 42 mA for a growth temperature of 750 ° C.
It has been found that the semiconductor laser grown at V / III = 400 has better characteristics.

In order to simplify the description of FIG. 3, which is a sectional view of the semiconductor laser, some layers are omitted.
Actually, between the p-type first cladding layer and the n-type block layer,
There is an etching stop layer group consisting of two layers.

The Al mixed crystal ratio of each layer is not limited to the value shown in the embodiment. For example, the active layer may be made of GaAs having an Al mixed crystal ratio of zero.

(Embodiment 4) In Embodiment 4, Embodiment 3
Of the second growth (after the p-type Al _0.5 Ga _0.5 As second cladding layer 8) is performed by LPE instead of MOCVD.
Performed by law. Each layer up to the Si-doped n-type AlGaAs block layer 6 on the n-type GaAs substrate is grown at a growth temperature of 7
It is the same until it is formed at 50 ° C. and V / III = 200 and the stripe is formed. Further, the Mg-doped p-type Al _0.5 Ga _0.5 As second cladding layer 8 ′ (1.5 ×
10 ¹⁸ / cm ³ , 1 μm setting), Mg-doped p-type GaAs
An s-contact layer 9 ′ (4 × 10 ¹⁸ / cm ³ , 1 μm setting) is formed.

When the operating current of the laser manufactured under the above conditions was examined, it showed 39 mA which was almost the same as that of the third embodiment. The LPE conditions were the same. The operating current of the laser produced at the MOCVD growth condition of 750 ° C. and V / III = 60 was 45 mA.
It was found that the laser produced at 50 ° C. and V / III = 200 had better characteristics.

(Embodiment 5) FIG. 7 shows a cross-sectional view of an AlGaAs semiconductor laser manufactured by the MOCVD method of Embodiment 5. This is a structure called a ridge type, and n-type Ga
On an As substrate 51 (carrier concentration 2 × 10 ¹⁸ / cm ³ ), a Si-doped n-type GaAs buffer layer 52 (1 × 10 ¹⁸ / cm ³ , thickness 0.5 μm) by MOCVD, Si-doped n-type Al _0.5 Ga _0.5 As clad layer 5
3 (4 × 10 ¹⁷ / cm ³ , thickness 1 μm), undoped Al _0.14 Ga _0.86 As active layer 54 (0.04 μ thickness)
m), Zn-doped p-type Al _0.5 Ga _0.5 As first cladding layer 55 (1 × 10 ¹⁷ / cm ³ , thickness 0.3 μm);
Zn-doped p-type GaAs etching stop layer 56 (1
× 10 ¹⁸ / cm ³ , thickness 0.003 μm), Zn-doped p-type Al _0.5 Ga _0.5 As second cladding layer 58 (1.
5 × 10 ¹⁸ / cm ³ , thickness 1 μm), Zn-doped p
A type GaAs cap layer 59 (3 × 10 ¹⁸ / cm ³ , thickness 1 μm) is formed. p-type GaAs cap layer 5
9. The p-type Al _0.5 Ga _0.5 As second cladding layer 58 is removed so that the stripe-shaped ridge remains. Next, MOC
By the VD method, the Si-doped n-type AlGaAs block layer 60 is formed.
⁽³ × 10 ¹⁸ / cm 3 set) is formed, the one formed on the p-type GaAs cap layer 59 is removed. Further, a Zn-doped p-type contact layer 61 (set at 3 × 10 ¹⁸ / cm ³ ) is formed by MOCVD. Thereafter, an n-electrode 63 is formed on the lower surface, and a p-electrode 64 is formed on the upper surface. The bar is divided into bars, and the light-emitting surfaces at both ends of the bar are coated with a reflective film and further divided into chips. The growth was performed at a growth temperature of 800 ° C. and V / III = 500. As a result of preparing a sample for SIMS in the same manner as in Example 3,
Zn-doped p-type Al _0.5 Ga _0.5 A inside and outside the stripe
The impurity concentration of the first cladding layer 55 is 1 × 10 ¹⁷ / cm
³ was the same as the setting. When the operating current of the semiconductor laser device was measured, it was 37 mA, and there was no significant difference in characteristics between the self-aligned type and the ridge type.

[0043]

By using the growth method of the present invention,
Al having low carrier concentration in both n-type and p-type
A crystal of _x Ga _{1 -x} As (x ≧ 0.5) can be obtained with high quality and good reproducibility. Further, a semiconductor laser having excellent characteristics can be manufactured with good yield and good reproducibility by using this growth method.

[Brief description of the drawings]

FIG. 1 is a diagram showing the dependence of the undoped AlGaAs film carrier concentration on the mixed crystal ratio under the crystal growth conditions of a growth temperature of 750 ° C. and V / III = 120.

FIG. 2 shows Al under crystal growth conditions at a growth temperature of 750 ° C.
FIG. 4 is a diagram showing the growth V / III dependence of the carrier concentration of a _0.6 Ga _0.4 As film.

FIG. 3 is a sectional structural view of a semiconductor laser device in Examples 3 and 4.

FIG. 4 is a diagram showing a SIMS profile inside a stripe of a semiconductor laser device in a real example 3;

FIG. 5 is a diagram showing a SIMS profile of a semiconductor laser device outside a stripe in a real example 3;

FIG. 6 is a diagram showing a SIMS profile of a semiconductor laser device manufactured by a conventional method in an off-stripe structure.

FIG. 7 is a sectional structural view of a semiconductor laser device according to a fifth embodiment.

[Explanation of symbols]

1, 51 n-type GaAs substrate 2, 52 n-type GaAs buffer layer 3, 53 n-type Al _0.5 Ga _0.5 As cladding layer 4, 54 undoped Al _0.14 Ga _0.86 As active layer 5, 55 p-type Al _0.5 Ga _0.5 As first cladding layer 6, 56 n-type AlGaAs block layer 8 and 58 p-type Al _0.5 Ga _0.5 As second cladding layer 9,61 p-type GaAs contact layer 10,63 n electrode 11,64 p electrode 56 n-type AlGaAs etching stop layer 59 p-type GaAs cap layer 60 n-type GaAs block layer

Claims (4)

[Claims] 1. The method according to claim 1, wherein Al _x
In the method of growing a crystal of a Ga _1-x As (x ≧ 0.5) compound semiconductor, the growth temperature is 750 ° C. or more and 850 ° C., and the ratio V / V of the group V source gas to the group III source gas is V /.
AlGaAs wherein III is 150 or more
A method for growing a crystal of an s-compound semiconductor. 2. The AlGa according to claim 1, wherein the Al _x Ga _1-x As (x ≧ 0.5) compound semiconductor is n-type, and Si is used as an n-type dopant.
A method for growing a crystal of an As compound semiconductor. 3. The A according to claim 1, wherein the Al _x Ga _{1 -x} As (x ≧ 0.5) compound semiconductor is a p-type, and a group II material is used as a p-type dopant.
A method for growing a crystal of an lGaAs compound semiconductor. 4. The method according to claim 1, wherein Al _x
In a method of manufacturing a semiconductor laser of Ga _1-x As (x ≧ 0.5) compound semiconductor, Al _x Ga _1-x As (x ≧ 0.5) having a carrier concentration of 1 × 10 ¹⁷ / cm ³ or less as a cladding layer.
0.5) The conditions for crystal growth of the compound semiconductor are that the growth temperature is 750 ° C. or more and 850 ° C., and the ratio V / III between the group V source gas amount and the group III source gas amount is 150 or more. A method for manufacturing a semiconductor laser.