JPS63314882A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To reduce the irregularity of characteristics by so specifying the thickness of an (AlzGa1-z)wIn1-wP layer interposed between (AlyGa1-y)wIn1-wP to thickness that quantum level becomes larger than the oscillation energy of an active layer. CONSTITUTION:An n-type (Al0.5Ga0.5)0.51In0.49P clad layer 2, a GaIn active layer 3, a lower p-type (Al0.5Ga0.5)0.51In0.49P clad layer 9, a p-type GaInP layer 5, an upper p-type (Al0.5Ga0.5)0.51In0.49P clad layer 6, a p-type GaAs cap layer 7 are formed on an n-type GaAs substrate 1. An SiO2 mask 10 is formed thereon, the layers 6, 7 are etched in mesa state to form an n-type GaAs layer 8. After the mask 10 is removed, a p-type GaAs contact layer 9 is formed. The layers 4 (0.3mum thick) and the layer 5(40Angstrom thick) are thinned, and the distance between the layer 3 and the layer 8 for absorbing a light is formed as designed to reduce the irregularity of characteristics between lots.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an AIGaInP semiconductor laser device that oscillates in a single transverse mode.

(Prior art) Recently, A that oscillates in a single transverse mode is formed by crystal growth using metal organic pyrolysis (hereinafter abbreviated as MOVPE).
As an IGaInP-based semiconductor laser device, the structure shown in Figure 3 has been reported (Extended Ab
strarts of the 18th Confe
rence on 5solid 5tateDevic
es and Materials, Tokyo,
1986. pp. 153-156).

This structure was formed on the n-type GaAs substrate 1 during the first growth.
P cladding layer 2% GaInP active layer 3, p type (Alo,
5Gao, s)o, 5tIno, 49P cladding layer 4,
A p-type GaAs cap layer 7 is sequentially formed. Next, mesa stripes are formed by photolithography using 5i02 as a mask. Then, with the 5i02 mask on, the second growth was performed and the etched area was
It is filled with a type GaAs layer 8. Next, the 5i02 mask is removed, and a p-type GaAs contact layer 9 is grown in a third growth so that an electrode can be formed on the entire p-side surface.

With this structure, current is blocked by the n-type GaAs layer 8 and is injected only into the mesa stripe portion. Furthermore, during etching to form the mesa stripe, the thickness of the p-type cladding layer other than the mesa stripe portion is etched to a thickness insufficient for confining light. Light is absorbed by the type GaAs layer 8 and guided only to the mesa stripe portion. In this way, in this structure, a current confinement mechanism and an optical waveguide mechanism are created at the same time.

(Problems to be Solved by the Invention) In the above structure, the etching at the time of forming the mesa stripe, which determines the distance between the active layer 3 and the n-type GaAs layer 8, is time-controlled etching. For this reason, the controllability and reproducibility of the thickness of the p-type cladding layer after etching is poor, and there is a problem in that the characteristics vary widely among the lofts of the device.

An object of the present invention is to provide a semiconductor laser device that solves this problem.

(Means for Solving the Problems) The present invention provides a GaAs substrate of a first conductivity type, which is lattice matched to (AlxGa1-x)wInl-wp(o≦x≦0.
3. W ~ 0.51) and (AlyGa1-y) wInl-wP (x + 0.4
The quantum level when a double heterostructure formed by a cladding layer consisting of is the second conductivity type (AlxGa1-z) with a film thickness larger than the oscillation energy of the active layer.
wInl-wP (z≦y-0,4) layer and a mesa stripe-shaped second conductivity type (AlyGa
t-y) wInt-wP cladding layer and a portion other than this mesa stripe-shaped cladding layer is made of GaAs of the first conductivity type.
It is characterized by having a JW.

(Function) When the configuration of the present invention described above is used, the current confinement mechanism is the same as the conventional structure, and the optical waveguide is also p-type (A
lyGal-y) wInl-wP (A12
Even if the Ga1-zIn1-wP layer in bulk has a composition that absorbs the light emitted from the active layer, in the present invention, the film thickness is quantized by the level, and the quantum level becomes larger than the oscillation energy of the active layer. Since the thickness is specified, the light from the active layer is
It is not absorbed in this layer, but seeps into the mesa-shaped cladding layer, and the transverse mode is controlled by the same mechanism as the conventional structure. Also, (AlzGax -x)wInl-wP(W~0.51
) For mixed crystals, if there is a difference in X of 0.4 or more, a hydrochloric acid-based etching solution can etch a crystal with a large composition of X more than 30 times faster than a crystal with a composition with a small composition of X. Therefore, in the manufacturing process of this structure, during the formation of mesa stripes, etching of the p-type cladding at locations other than the mesa stripe portions can be stopped between the upper and lower p-type cladding layers for a considerable period of time. Therefore, by using a growth method with excellent film thickness controllability, such as MOVPE, an element with small variations in characteristics between lofts can be obtained with good reproducibility.

(Example) Hereinafter, an example of the present invention will be described using the drawings. FIG. 1 is a sectional view of a semiconductor laser device showing an embodiment of the present invention, and FIG. 2 is a manufacturing process diagram of this semiconductor laser device.

First, in the first growth, n-type (Alo,
5Gao, s)o, 5xIno, 4sP cladding layer 2 (
n=I x 1018cm-3; thickness 1.2pm),
GaInP active layer 3 (undoped; thickness 0.111 m)
, lower p-type (Alo, 5Gao, s) o, 5IIno,
49P cladding layer 4 (p=5X1017cm-'; thickness O,:%m), p"I GaInP layer 5 (p=1 01
8cm-340 people), upper p-type (Alo, 5Gao, s
)o, 5xIno, 49P cladding layer 6 (p==5X1
017 cm-3; thickness lpm) and a p-type GaAs cap layer 7 (p=2×1018 cm=; thickness 0.5 pm) (FIG. 2(a)). For growth, reduced pressure M
The growth conditions using the OVPE method were a temperature of 700°C, a pressure cuff of 0 Torr, V/III = 200, and a carrier gas (H
The total flow rate of z) was set to 15 (1/m1n). Raw materials include trimethylindium (TMI: (CHa)aIn), triethylgallium (TEG: (CHa)aGa), trimethylaluminum (TMA: (CHa)sAl), arsine (AsHa), phosphine (PHa), p-type dopant: Dimethylzinc (DMZ: (CHs)2Zn)
, n-type dopant: hydrogen selenide (H2Se) was used. A striped 5i02 mask 10 was formed on the thus grown ware by photolithography (FIG. 2(b)). Next, using this 5i0210, the p-type GaAs cap layer 7 was etched into a mesa shape using a phosphoric acid-based etching solution. Continuing, (Alo, 5Gao, s)
Etching rate for o, 5IIno, oP is 60
Upper p-type (Alo, 5Gao, s)o, 5xIno
, the 49P cladding layer 6 was etched into a mesa shape (second
Figure (C)). And M with 5i02 mask 10 on
A second growth is performed by OVPE to form an n-type GaAs layer 8.
(Fig. 2(d)). Next 5i02 mask 10
In order to remove the contact layer 9 by etching (Fig. 2(e)), a third growth is performed by MOVPE to form a P-type GaAs contact layer 9.
(Fig. 2(f)). The growth conditions for the second and third times are the same as those for the first growth described above. Finally, both p and n electrodes are formed and the capacitance length is 250 pm.
Separated into individual chips.

Elements obtained from 30 laser wafers of the present invention produced by the above method and 30 conventional laser wafers (
Table 1 shows the average value of the maximum optical output in fundamental transverse mode oscillation of 30 pieces for each lot.

As can be seen from Table 1, by using the present invention, the distance between the active layer and the light-absorbing GaAs layer can be made as designed, and variations in properties between lots can be suppressed.

In the embodiments described above, the active layer is GaInP and the cladding layer is (Alo, 5Gao, s)o, 5xIno, 49P.
However, in order to change the oscillation wavelength (make it shorter), the A1 composition of the active layer may be increased within a range that satisfies the requirements of the present invention. Further, in the embodiment, the composition of the three cladding layers is the same, but the composition may be changed depending on the characteristics desired for the laser.

(Effects of the Invention) As described above, according to the present invention, it is possible to obtain a fundamental transverse mode control AIGaInP semiconductor laser device with small variations in characteristics between growth lots.

[Brief explanation of the drawing]

Claims (1)

[Claims] On a first conductivity type GaAs substrate, (Al_xGa_1_-_x)_wIn_1_-_wP is lattice-matched to this substrate.
(0≦x≦0.3, W~0.51);
Sandwiching this active layer (Al_yGa_1_-_y)_wIn_1_-_wP
A double heterostructure formed by a cladding layer consisting of (x+0.4≦y) is provided, and both sides are (Al_yGa_1_−_y
)_wIn_1_−_wP, the quantum level is
The second conductivity type (Al_zGa_1_-_z)_wIn_1_-_ has a film thickness larger than the oscillation energy of the active layer.
wP (z≦y-0.4) layer and a mesa stripe-shaped second conductivity type (Al_yGa_1_-_
y) _wIn_1_-_wP cladding layer and a portion other than this mesa stripe-shaped cladding layer with Ga of the first conductivity type.
A semiconductor laser device characterized by providing an As layer.