JPS60163487A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To enable the manufacture by a method wherein a semiconductor substrate is provided with a mesa provided by including the first semiconductor layer, the second semiconductor layer having a smaller forbidden band width than an active layer and the conductivity type different from that of the substrate, and a double-hetero structural semiconductor layer thereon. CONSTITUTION:The first semiconductor layer 11 is grown on the P type GaAs substrate 1 by the MOCVD method, and an SiO2 strips 30 is formed on the surface. The whole is inserted into an MOCVD furnace and then etched on heating by passing HCl and AsH3, and an N type GaAs is grown by feeding an organic metal serving as the grown source, AsH3, and a dopant gas, resulting in the formation of the second semiconductor layer 12. The SiO2 stripe 30 is removed, and the first clad layer 3, active layer 4, and second clad layer 5 are laminated again by the MOCVD method. The wafer thus manufactured forms a semiconductor laser by the process for the formation of the normal device.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a semiconductor laser that oscillates in a stable single-transverse mode with a low threshold value.

(Prior art) In general, semiconductor lasers have a stable monolayer with a low threshold value.
Transverse mode oscillation is important as a light source for optical communications and optical information processing. Conventionally, when producing semiconductor saw 4't-1, liquid phase epitaxial growth (hereinafter referred to as LPE growth) was used.
Although crystal growth of semiconductor lasers by the method has been mainstream, crystal growth by the organic gold tetradecomposition method (hereinafter referred to as MOCVD method) is attracting attention from the viewpoint of uniformity and mass production.

Figure 1 (al is a cross-sectional view of the active layer of a semiconductor laser fabricated by LPE growth on a V-groove substrate). The difference is that the forbidden band width is smaller than that of the active If4.
Provide a V-groove that reaches . The first cladding layer 3 and the active r
-42 When laminated one after another, the l-th glue 2nd layer 3 is buried flatly on the V-groove.

A flat active layer 4 is crystal-grown on this first glue layer 3.

The active layer 4 on this V-groove is separated from the laminar flow block layer 2 or the active layer 4 formed on the flat part other than the V-groove via the first cladding layer 3 with respect to the semiconductor substrate l. Therefore, an excellent semiconductor laser with a complete optical waveguide mechanism and stable single-transverse mode oscillation can be obtained. However, a certain mixed crystal system 1, for example, a GaInP mixed crystal system on a GaAs substrate, is very difficult to grow by LPE and cannot be manufactured without using a non-equilibrium growth method such as MOCvD method.

-1. When manufacturing this semiconductor laser by the i-MOCVD method, this MOCVD method has the advantage of uniformity and heritage, but as shown in Figure 1 (b), The first cladding layer 3 and the active layer 4 are left as they are, and there is a drawback that it is not possible to obtain the active layer shape as shown in FIG. 1+a).

(Object of the Invention) An object of the present invention is to eliminate such drawbacks and to provide a semiconductor laser having a figure-7 waveguide mechanism and a first-flow blocking layer, which can be easily manufactured by the Lecture 1M0 cVD method. be.

(@Akira's configuration) The configuration of the present invention is that in a semiconductor laser having a double hetero semiconductor layer with an active layer sandwiched between cladding layers @1 and $2, the active layer is placed on a semiconductor substrate. A mesa provided including a first semiconductor layer whose forbidden band width is larger than that of the active layer and which covers the upper surface of the substrate other than the upper surface of this mesa and which is prohibited from the active layer. A second semiconductor layer having a small tttl width and having a conductivity different from that of the semiconductor substrate, and the double heterostructure semiconductor layer provided above the second semiconductor layer. do.

According to the configuration of the present invention, the active layer on the upper part of the mesa, which has a second semiconductor layer on the side surface which has a smaller bandgap than the active layer and has a different conductivity from the semiconductor substrate, has a waveguide mechanism, and the second semiconductor layer has a waveguide mechanism. Because the conductivity of the layer is different from that of the semiconductor substrate, the t-current is effectively injected into the light-emitting region of the active layer and oscillates, and the LPE
Illustrative characteristics of growth Figure 21 is a cross-sectional view of an embodiment of the present invention using a refined MOCVD method and photolithography that can be fabricated without using sound. In this embodiment, a mesa 20 including a first semiconductor node 11 having a larger forbidden band width than the active layer 1-4 is provided on a semiconductor substrate l. On both sides of this mesa 20, an active layer 4 and a second semiconductor layer 12 having a small forbidden band width and different conductivity from the semiconductor substrate 1 are provided.

Above the mesa 20 and the second semiconductor layer 12, a first cladding layer 3. Active layer 4. A double heterostructure consisting of a second cladding layer 5 is provided. The central part of the flat active layer 4 above this mesa 20 is in contact with the first semiconductor layer 11 through the first cladding layer 31, and both ends thereof absorb light through the first cladding layer 3. The second semiconductor layer 12 has a smaller forbidden band width than the active layer 4. Therefore, the active layer 4 above the mesa 20 has an optical waveguide mechanism, and the second semiconductor layer 12 effectively injects an undercurrent into the center of the active layer 4 above the mesa 20. Therefore, a semiconductor laser having this structure oscillates in a stable single-transverse mode with a low threshold value.

FIGS. 3A to 3E are cross-sectional views showing all the embodiments of FIG. 2 in the order of manufacturing steps. First, Figure 3 ta
), a p-type AJ30.3 GaO,7 which becomes the first semiconductor layer 11 is formed on a p-type GaAs substrate l.
A S semiconductor layer 91μm grown by 1M0cVD method,
The surface is coated with S by photolithography and chemical etching.
A stripe 30 of iOz and a width of 3 μm is formed. Next, insert MOCVD furnace IC L, HCl3 and AsH3't
aL heating and etching (Fig. 3 tb)),
After that, organic gold 4, A s Ha, and dopant gas, which will serve as a growth source, are sent to form n-type GaAs 1Q. 7 μm is grown to form a second semiconductor layer 12′t- (FIG. 3(C))
. Then chemically etched 5iOz stripes 30
1, d)), and after appropriate pretreatment, the p-type A4o, aGao, yAs7 layer 3, which will become the first cladding layer 3, is deposited with a thickness of 0.3 μm by MOCVD again.
, a non-doped GaAs layer 0.1 serving as the active layer 4
n-type A4o, aGa that becomes the cladding layer 5 of μm+i2
O,7A81-k 1.5 μm, dipping layer (third
Figure (e)). Furthermore, in reality, n
A full G a As layer of the type is grown. The wafer thus produced is used to form a semiconductor laser through a normal device forming process.

(Effect of the invention) Since the active layer 4 of this semiconductor laser is a GaAs layer and the second semiconductor 1512 is also a GaAs layer, the mesa 20
Since a waveguide mechanism is formed in the upper active layer 4, "straight single-transverse mode oscillation" is possible.

fc1 In manufacturing the semiconductor laser of this example, the third
The 5iOz stripe 30 is removed from the state of 1 tb), and a GaAs layer that will become the second semiconductor layer 12 is uniformly deposited on the mesa 20.
Another method is to form the fJ layer using the J-QMOCVD method and, depending on the difference in etching rate between the upper and lower parts of the mesa in chemical etching, to perform GaAs1 etching to produce the structure shown in FIG. 3 (dl). When the forbidden band width of the semiconductor substrate 1 is larger than that of the semiconductor layer, the first semiconductor layer 11 may not be laminated and the semiconductor substrate 1 may be used instead.

[Brief explanation of the drawing]

Figure 1 tag, tb> shows LPE and MO on the groove substrate.
2 is a cross-sectional view showing a state in which 1st dipping is performed by CVD, FIG. 2 is a schematic cross-sectional view of an embodiment of the present invention, and FIGS. 3(a) to (el are cross-sectional views of FIG. In the figure, l...semiconductor substrate, 2...t (M block no, 3... first cladding layer, 4...
...Activity]4.5...Second cladding layer, 1
1... Semiconductor layer of conduit l, 12... Second
semiconductor layer, 20... mesa, 30...
It is 5 in 2 stripes. 3 pieces of 1st Warabiyuzumi

Claims (1)

[Claims] In a semiconductor laser having a double heterostructure semiconductor layer in which an active layer is sandwiched between first and second cladding layers, a first cladding layer having a larger forbidden band width than the active layer is disposed on a semiconductor substrate.
a second semiconductor, which is coated with gold on a side surface other than the upper surface of the mesa and the upper surface of the substrate, has a band gap smaller than that of the active layer, and has a conductivity different from that of the semiconductor substrate; 1. A semiconductor laser comprising: a double heterostructure semiconductor layer, the double heterostructure semiconductor layer being provided on top of the second semiconductor layer.