JP3143105B2 - Method for manufacturing semiconductor laser device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor laser device, and more particularly to an AlGaInP semiconductor laser device suitable as a short wavelength laser light source for an optical disk memory.

[Conventional technology]

Conventionally, an AlGaInP semiconductor laser having a transverse mode control structure has been disclosed in Electronics Letters 23 (1987).
Years) 938 to 939 (Electron. Lett. 23 (1987) pp.
938-939).

[Problems to be solved by the invention]

In the above prior art, the carrier concentration in the p-type AlGaInP optical waveguide layer is as low as 2 to 3 × 10 ¹⁷ cm ^{-3 at the} maximum, and the device resistance is about
Since it is as high as 10Ω, there is a problem that the laser oscillation maximum temperature and the reliability cannot be sufficiently obtained.

An object of the present invention is to provide an element structure capable of increasing the effective carrier concentration of a p-type AlGaInP mixed crystal and reducing the element resistance, and a method of manufacturing the same. Another object is to improve the laser oscillation maximum temperature and reliability.

[Means for solving the problem]

The above object can be achieved by laminating an n-type mixed crystal containing an n-type impurity in the form of a hydrogen compound on a p-type AlGaInP mixed crystal.

In order to further improve the p-type AlGaInP mixed crystal carrier concentration, an annealing effect is effective. That is,
After epitaxially growing the above-mentioned multilayer, the temperature range is then 200 to 900 ° C., especially 700
Annealing may be performed at a temperature in the range of up to 900 ° C. for a time in the range of 10 to 60 minutes.

Further, the present invention can be implemented by the following method. That is, on a semiconductor substrate, a semiconductor light-emitting active layer having a small band gap is formed by a p-type cladding layer having a large band gap provided below and an n-type cladding layer being an n-type semiconductor layer having a large band gap provided above. Or n in which the semiconductor active layer is provided as a lower layer.
Having a double hetero structure in which an n-type semiconductor layer is stacked above the upper p-type cladding layer and sandwiched between the n-type semiconductor layer and the p-type cladding layer provided on the upper side. An object is to manufacture a semiconductor laser device by introducing an impurity in the form of a hydrogen compound and epitaxially growing it by a vapor phase growth method to provide the double heterostructure.

[Action]

By growing an n-type mixed crystal doped with an n-type impurity as a hydrogen compound on the p-type AlGaInP mixed crystal,
Hydrogen molecules decomposed and occluded in the n-type mixed crystal are p-type
It diffuses into AlGaInP mixed crystals. This diffusion of hydrogen molecules promotes the diffusion of the p-type impurity Zn located at the interstitial site in the p-type AlGaInP mixed crystal, and replaces the lattice site with ionization to improve the activation rate. In order to effectively obtain this effect, it is desirable that the amount of the hydrogen compound n-type impurity doped in the n-type mixed crystal is as large as possible.

Further, annealing after growing an n-type mixed crystal on the p-type AlGaInP mixed crystal is effective for improving the carrier concentration. This is the temperature range 200-900 ° C, especially 600
It is considered that the diffusion distance of the p-type impurity is increased in the range of -900 ° C, and the impurity located at the interstitial site is replaced with the lattice site and ionized.

The n-type mixed crystal does not need to be directly laminated on the p-type AlGaInP mixed crystal, and a film having a thickness capable of transmitting hydrogen molecules in the n-type mixed crystal may be interposed.

By the above-described operation, the conventional p-type AlGaInP has a maximum
Relative to 3 × 10 ¹⁷ to cm only carrier concentration of ^-3 obtained did not, it was found that the carrier concentration of about 3 times the 6 to 9 × 10 ¹⁷ cm ^-3 is obtained.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIG. FIG. 3 is a schematic view showing a manufacturing process of this embodiment. In FIG. 3A, first, a p-GaAs buffer layer 2 (d = 0.5 to 1.0 μm, n _A = 1 × 10 ¹⁸ cm ⁻³ , p-Ga) is formed on a p-GaAs substrate 1.
_0.51 In _0.49 P layer 3 (d = 0.1 to 0.2 μm, n _A = 1 × 10 ¹⁸ c
m ^-3 ), p- (Al _x Ga _{1 -x} ) _0.51 In _0.49 P cladding layer 4
(D = 0.6 to 0.9 μm, n _A = 2 to 3 × 10 ¹⁷ cm ⁻³ ), p-Ga
_0.51 In _0.49 P thin film layer 5 (d = 0.002-0.006 μm, n _A = 8 ×
10 ^{17 -1} × 10 ¹⁸ cm ^-3 ), n-Al _α Ga _1-α As (0α
1) or n- (Al _x Ga _1-x ) _0.51 In _0.49 P (0 <x1)
Cap layer 14 (d = 0.5 to 1 μm, n _D = 1 × 10 ^{18 to} 5 × 10
¹⁸ cm ^-3 ) is grown epitaxially at a growth temperature of 650 to 700 ° C. by organic metal vapor deposition (MOCVD), molecular beam epitaxy (MBE) or gas source molecular beam epitaxy (MOMBE). At this time, the n-type impurity is Se, which is introduced as a hydrogen compound of hydrogen selenide (H ₂ Se), and the p-type impurity is Zn, which is dimethyl zine (DMZ).
c) introduced in the form of an organometallic compound. Subsequently, annealing is performed in the same growth furnace at a temperature of 700 to 900 ° C. for 10 to 30 minutes. Atmosphere at this time, is using arsenic atmosphere when the material of the cap layer 14 of _{n-Al α Ga 1-α} As, n-
In the case of (Al _x Ga _1-x ) _0.51 In _0.49 P, a phosphorus atmosphere is used.
Next, the in FIG. 3 (b), the wafer is taken out of the epitaxial growth than the growth reactor, sulfuric acid, n-Al with phosphoric acid or a halogen acid solution _α Ga _1-α As or n-(Al
_x Ga _1-x ) _0.51 In _{0.49 The} cap layer 14 composed of the P layer is removed by etching. Next, in FIG. 3C, an SiO ₂ insulating film 15 (d = 0.2 to 0.3 μm) is formed, and the resist film 16 is patterned by lithography. Further, in FIG. 3 (d), the SiO ₂ insulating film 15 is etched with a hydrofluoric acid solution, and the layer 3
4 and 5 are removed by etching to form a regular mesa-shaped ridge stripe. Next, after the resist 16 is removed, the n-GaAs light absorption and current confinement layer 6 is left while the SiO ₂ insulating film mask 15 is left.
(D = 0.6 to 1.2 μm, n _D = 2 to 4 × 10 ¹⁸ cm ⁻³ ) is selectively grown, and the ridge step is buried flat. (FIG. 3E) Thereafter, the SiO ₂ insulating film mask 15 is removed, and p- (Al _x Ga _{1 -x} )
_0.51 In _0.49 P clad layer 7 (d = 0.2 to 0.5 μm, n _A = 2
3 × 10 ¹⁷ cm ^-3 ), undoped (Al _x Ga _1-x ) _0.51 In _0.49 P
Active layer 8 (d = 0.03 to 0.08 μm, y = 0) n− (Al _x G
a _1-x ) _0.51 In _0.49 P cladding layer 9 (d = 0.8 to 1.0 μm, n _D
= 7 to 9 × 10 ¹⁷ cm ⁻³ ) n-Ga _0.51 In _0.49 P layer 10 (d = 0.
1 to 0.2 μm, n _D = 1 to 2 × 10 ¹⁸ cm ^-3 ) n-GaAs cap layer
11 (d = 1.0 to 3.0 μm, n _D = 4 to 6 × 10 ¹⁸ cm ⁻³ ) are successively epitaxially grown, and subsequently, at a temperature of 70 in the same growth furnace.
Annealing is performed in the range of 0 to 90 ° C. for 10 to 30 minutes (FIG. 3 (5)). Next, in FIG. 3 (g), an n-electrode 12 and a p-electrode 13 are deposited and cleaved by scribing to form a first electrode.
Cut out the element shown in the figure.

In this embodiment, conventionally, p- (Al _x Ga _1-x ) _0.51 In
_0.49 Maximum carrier concentration of P cladding layers 4 and 7 is 2-3
While the carrier concentration was only × 10 ¹⁷ cm ⁻³ , the carrier concentration could be increased to a maximum of 6 to 9 × 10 ¹⁸ cm ⁻³ .
As a result, the resistivity of the p (Al _x Ga _{1 -x} ) _0.51 In _0.49 P cladding layer can be reduced, so that the device resistance can be reduced from 8 to 10 Ω to 4 to 5 Ω. The threshold current of this device is 20 to 50 mA, and the maximum laser oscillation temperature is 100 to 1
The temperature could be increased to 20 ° C. Regarding the reliability of the device, when an asymmetric coating was applied to both end surfaces of the device, no remarkable deterioration was observed even when the constant light output operation of 20 mW at a temperature of 50 ° C. was continued for 1000 hours or more.

Embodiment 2 Another embodiment of the present invention will be described with reference to FIG. In this embodiment, the semiconductor device is manufactured in exactly the same manner as in the first embodiment except that an inverted mesa-shaped ridge stripe is formed. In this device, the same effect as that of the device of Example 1 was obtained. further,
The astigmatic difference was 2 to 4 μm in the range of light output of 1 to 10 mW.

〔The invention's effect〕

According to the present invention, since the carrier concentration of the p-type AlGaInP mixed crystal can be improved to about 3 to 9 × 10 ¹⁷ cm ^{−3, which} is almost three times that of the conventional one, a p-type AlGaInP mixed crystal with low resistivity can be obtained, and the Can be reduced to 4 to 5Ω. For this reason, the maximum laser oscillation temperature of the device can be improved to 100 to 120 ° C. In terms of device reliability, when asymmetrical coating is applied to both end surfaces of the device, 1000 m at a constant light output operation of 20 mW at a temperature of 50 ° C. No remarkable deterioration was observed even after the lapse of time.

It goes without saying that the element structure is not limited to the above embodiment. Further, the conductivity type of the element may be reversed. Furthermore, although an AlGaInP mixed crystal semiconductor laser has been described as an example, the same can be said for an InGaAsP or AlGaInP mainly containing P.

[Brief description of the drawings]

1 and 2 are longitudinal sectional views of Examples 1 and 2 of the present invention, respectively, and FIG. 3 is a process chart showing an example of device fabrication of the present invention. 1 ... P-GaAs substrate, 2 ... P-GaAs buffer layer, 3 ...
... p-Ga _0.51 In _0.49 P layer, 4 ... p- (Al _x Ga _1-x ) _0.51
In _0.49 P cladding layer, 5 ... p-Ga _0.51 In _0.49 P thin film layer, 6 ... n-GaAs light absorption and current confinement layer, 7 ... p-
_{(Al x Ga 1-x)} 0.51 In 0.49 P cladding layer, 8 ...... (Al _x Ga
_1-x ) _0.51 In _0.49 P active layer, 9 ... n- (Al _x Ga _1-x )
_0.51 In _0.49 P cladding layer, 10 n-Ga _0.51 In _0.49 P
Layer, 11 n-GaAs cap layer, 12 n-electrode, 13
p-electrode, 14 ... n-Al _α Ga _1-α As cap layer or n-
(Al _x Ga _1-x ) _0.51 In _0.49 P cap layer, 15: SiO ₂ insulating film, 16: resist.

Continuation of front page (56) References JP-A-2-262388 (JP, A) JP-A-1-286482 (JP, A) IEEE J.I. Quantum Electronics Vol. QE-23 No. 6 (1987) p. 704-711 Appl. Phys. Lett. Vol. 53 No. 9 (1988) p. 758-760 (58) Field surveyed (Int. Cl. ⁷ , DB name) H01S 5/00-5/50

Claims (6)

(57) [Claims] Claims: 1. A p-type for a site requiring a high carrier concentration
A step of laminating an n-type semiconductor layer in which an n-type impurity is introduced in the form of a hydride on the AlGaInP-based compound semiconductor material layer or the p-type InGaAsP-based compound semiconductor material layer, by annealing these layers, A method for manufacturing a semiconductor laser device, comprising a step of giving a desired carrier concentration to the p-type AlGaInP-based compound semiconductor material layer or the p-type InGaAsP-based compound semiconductor material layer. 2. A p-type for a site requiring a high carrier concentration.
A step of desirably laminating an n-type semiconductor layer in which n-type impurities are introduced in the form of a hydride on an AlGaInP-based compound semiconductor material layer or a p-type InGaAsP-based compound semiconductor material layer. Annealing in a temperature range of 900 ° C. causes the p-type AlGaInP-based compound semiconductor material layer or the p-type InGaAsP-based compound semiconductor material layer to have a thickness of 6 × 10 ¹⁷ cm.
^A method for manufacturing a semiconductor laser device, comprising a step of giving a carrier concentration of ^-3 or more. 3. A semiconductor active layer having a small band gap is provided above a semiconductor substrate, and a p-type cladding layer having a large band gap provided below and an n-type cladding layer provided as an n-type semiconductor layer having a large band gap provided above. A double hetero structure sandwiched between them, or an n-type cladding layer in which the above-mentioned semiconductor active layer is provided in a lower layer and a p-type cladding layer provided in an upper side, and an n-type semiconductor layer is provided above the upper p-type cladding layer Having a double heterostructure, and including a p-type AlGaInP-based compound semiconductor material layer or a p-type InGaAsP-based compound semiconductor material layer in a p-type clad layer requiring a high carrier concentration, and the p-type AlGaInP-based compound semiconductor An n-type impurity is interposed in the material layer or the p-type InGaAsP-based compound semiconductor material layer by interposing a film having a thickness through which hydrogen molecules can pass, or directly into the n-type semiconductor layer to be laminated. Introducing the compound in the form of a hydrogen compound, and epitaxially growing the layers by vapor phase epitaxy to form the double heterostructure, wherein the p-type AlGaInP-based compound semiconductor material layer or p-type I
A method for manufacturing a semiconductor laser device, wherein a desired carrier concentration is provided in an nGaAsP-based compound semiconductor material layer. 4. A method for manufacturing a semiconductor laser device according to claim 3, wherein said semiconductor substrate is a p-type semiconductor substrate, and a desired portion of said p-type cladding layer exists in a ridge-shaped stripe structure. And the p-type cladding layer is 3 ×
A method for manufacturing a semiconductor laser device, characterized in that the carrier concentration exceeds 10 ¹⁷ cm ^-3 . 5. The method for manufacturing a semiconductor laser device according to claim 4, wherein said n-type semiconductor layer is n-type (Al _x Ga _{1 -x} ) _0.51 In _0.49 P (0 <x ≦ 1). Layer or n-type Al
_A method for manufacturing a semiconductor laser device, comprising an _α Ga _1−α As (0 ≦ α ≦ 1) layer. 6. A p-type AlGaInP-based compound semiconductor material layer or a p-type InGaA as a first p-type cladding layer on a semiconductor substrate.
forming a p-type semiconductor layer having a thickness capable of transmitting hydrogen molecules on the sP-based compound semiconductor material layer and the p-type AlGaInP-based compound semiconductor material layer or the p-type InGaAsP-based compound semiconductor material layer; Forming an n-type semiconductor layer introduced in the form of a hydride, annealing the prepared semiconductor laminate, and removing the n-type semiconductor layer in which the n-type impurity has been introduced in the form of a hydride , The p-type
Processing a semiconductor laminate including the AlGaInP-based compound semiconductor material layer or the p-type InGaAsP-based compound semiconductor material layer and the p-type semiconductor layer having a thickness capable of transmitting hydrogen molecules into a ridge-shaped stripe; Embedding the ridge step with a semiconductor material different from the semiconductor laminate constituting the ridge-shaped stripe, forming a semiconductor active layer, and forming a second n-type cladding layer A method for manufacturing a semiconductor laser device, comprising: