JPS59105394A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To reduce the transmission threshold value, improve the transmission efficiency, and contrive to stabilize for a long period by a method wherein an active layer in a semiconductor laminated body is constructed in a super lattice structure, and a conductive layer formed on the semiconductor laminated body is formed into a specific shape. CONSTITUTION:The semiconductor layer 3 constituting the semiconductor laminated body 5 has the super lattice structure wherein a semiconductor layer 21 made of e.g. single crystal GaAs and having the thickness of several 1,000Angstrom or less as a quantum well layer and a semiconductor layer 22 made of e.g. AlzGa1-zAs (0<Z<1) and having the thickness of several 1,000Angstrom or less as a barrier layer are laminated in multi-layer successively and alternately. Besides, the conductive layer 9 extends between surfaces V1 and V2 parallel with cleavage end surfaces F1 and F2 passing inside from cleavage end surfaces F1 and F2, but has the structure of no extension between the surface V1 and the extended surface P1 of the cleavage end surface F1 and between the surface V2 and the extended surface P2 of the cleavage end surface F2. Thereby, even when atoms decreasing the energy band gap are not introduced, the light absorption coefficients of the sides of the cleavage end surfaces F1 and F2 of the semiconductor layer 3 become smaller than those of the other region by means of laser oscillation wave length.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a semiconductor substrate having a first conductivity type.
a first semiconductor layer having a first conductivity type as a cladding layer; a second semiconductor layer as an active layer; and a second conductivity type opposite to the first conductivity type as a second cladding layer. a third semiconductor layer having a mold and a third semiconductor layer stacked in that order, the semiconductor stack has first and second inter-fold end faces facing each other in parallel; A first conductive layer as a first electrode is formed on the surface of the semiconductor laminate facing the semiconductor substrate described above, and a first conductive layer as a first electrode is formed on the surface of the semiconductor laminate facing the third semiconductor layer described above. The present invention relates to a semiconductor laser device in which a second conductive layer is formed.

Conventionally, as such a semiconductor laser device, one having the configuration described below with reference to FIG. 1 has been proposed.

For example, on an N-type semiconductor substrate 1 made of single crystal GaAs, a cladding layer such as single crystal AI, Ga, -3
an N-type semiconductor layer 2 consisting of As (0<x<1>;
A semiconductor layer 3 as an active layer made of, for example, single crystal Qa AS and, for example, single crystal A1yGa, -yAs (0<
P-type semiconductor layers 4 (y<1) are stacked in this order to form a semiconductor stacked body 5. In this case, the semiconductor laminate 5 has inter-fold end faces F1 and F2 that are parallel to each other and face each other.

Such a semiconductor stack 5 is obtained by sequentially forming semiconductor layers, which will become semiconductor layers 2.3 and 4, on a semiconductor stack, which will become semiconductor substrate 1, by epitaxial growth.
It is formed by forming a semiconductor laminate that will later become the semiconductor laminate 5, and then folding the semiconductor laminate.

Furthermore, a conductive layer 8 as an electrode is formed on the surface of the semiconductor laminate 5 on the semiconductor substrate 1 side.

In this case, the conductive layer 8 extends between the extension surface P1 of the interfold end surface F1 and the extension surface P2 of the interfold end surface F2.

Furthermore, on the surface of the semiconductor layer 4 side of the semiconductor laminate 5 described above, a conductive layer 9 serving as an electrode facing the conductive layer 8 is provided.
is formed.

In this case, the conductive layer 9 also extends between the extension surface P1 of the interfold end surface [1 and the extension surface P2 of the interfold end surface F2.

The above is the configuration of a conventionally proposed semiconductor laser device.

According to this configuration, if a DC power source with the conductive F9 side positive is connected between the conductive layers 8 and 9, carriers are injected into the semiconductor layer 2, and light is emitted within the semiconductor layer 2. obtained, this propagates within the semiconductor layer 2, and the inter-fold end face "
1 and F2 are repeated, and thus laser oscillation is obtained, and the laser oscillation light is reflected on the interfold end faces F1 and F2.
A function as a semiconductor laser device is obtained by emitting light to the outside from either one of the two.

By the way, in the case of the conventional semiconductor laser 'JA neck structure shown in FIG. Then, the conductive layer 9 extends to the extension surface P of the inter-fold end surface F1.
1, since it extends between the folded end face F2 and the extended face P2, the chili I7 to be injected into the semiconductor layer 3 is extended between the folded end face F2 and the extended face P2.
It also exists in the areas on the 1 and F2 sides. however,
The honeycomb of the gear carrier in the region on the side of the inter-fold end surfaces F1 and F2 of the semiconductor layer 3 has a part of its carrier on the inter-fold end surfaces F1 and F
2, the inter-fold end face F1 of the semiconductor layer 3
And it is decreased more than jJ31J in the area other than the area on the F2 side. Therefore, the inter-fold end faces F1 and F of the semiconductor layer 3
The region on the second side has a lower energy bandgap than the other regions. Therefore, the light absorption coefficient at the wavelength of laser oscillation in the region on the inter-fold end faces F1 and F2 side of the semiconductor layer 3 is larger than that in other regions (J).

Therefore, in the case of the conventional semiconductor sheet 1F device shown in FIG. 1, during laser oscillation, the regions on the inter-fold end faces F1 and F2 side of the semiconductor layer 3 have a higher temperature than other regions, and Thermal distortion occurs in the end faces F1 and F2, and the inter-fold end faces F1 and F2 are oxidized, thereby degrading the inter-fold end faces F1 and F2.

Therefore, the conventional 1''1' conductor laser device shown in FIG. 1 has the disadvantage that it cannot stably function as a semiconductor laser device with desired characteristics over a long period of time.

Furthermore, a configuration similar to that described below with reference to FIG. 2 has been proposed in the past.

In FIG. 2, parts corresponding to those of the conventional semiconductor laser device shown in FIG. 1 are designated by the same reference numerals (=J, and detailed description thereof will be omitted.

The conventional semiconductor laser device shown in FIG. 2 is the conventional semiconductor laser device shown in FIG. In the 1f device, the semiconductor stack 5
Inside, on the inter-fold end faces F1 and F2, a semiconductor region G1 having a depth reaching the semi-semiconductor substrate 1 from the semiconductor layer 4 side and having a higher energy band gap than the semiconductor layer 2.
It has the same structure as the conventional semiconductor laser device shown in FIG. 1, except that the inter-fold end faces F1 and F2 are formed by the end faces of the semiconductor regions G1 and G2.

The above are other examples of conventionally proposed semiconductor laser devices.

According to this semiconductor laser device having a J-shaped configuration,
This is the same as the case of the conventional semiconductor laser device shown in Fig. 1, except for the matters mentioned above. The function as a 17" device can be obtained.

In addition, in the case of the conventional semiconductor laser device shown in FIG. 2, the semiconductor regions G1 and G2 numbered on the inter-fold end faces F1 and F2 of the semiconductor layer 3 have a high energy band gap, so that the laser oscillation is difficult. Semiconductor regions G1 and G at wavelength
The light absorption coefficient in the semiconductor layer 3 is lower than that in the semiconductor layer 3.

Therefore, the conventional semiconductor laser device shown in FIG. 2 does not have the drawbacks mentioned above in the conventional semiconductor laser device shown in FIG.

However, in the case of the conventional semiconductor laser device shown in FIG.
: 2, and the semiconductor layer 3 does not constitute a waveguide extending to the sugar end face F1 and 2. Therefore, in the semiconductor regions G1 and G2, the diffraction loss of light is Therefore, the conventional semiconductor laser device shown in FIG. 2 has the drawbacks of a large oscillation threshold and low oscillation efficiency.

Furthermore, a device having the configuration described below with reference to FIG. 3 has been proposed in the past.

In FIG. 3, parts corresponding to those of the conventional semiconductor layer assembly shown in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

The conventional semiconductor laser device shown in FIG. 3 is similar to FIG.
2 and extends between planes V1 and 72 parallel to plane V1.
and the extended surface 1) of the inter-fold end surface F1, and between the surface 2 and the extended surface P2 of the inter-fold end surface F2, and the semiconductor laminate 5, In the region below the conductive layer 9, from the conductive layer 9 side to a depth reaching the semiconductor layer 2, atoms that lower the 1 energy band yield, such as ZO, are introduced as shown by reference numeral 15C'. Except for this, the structure shown in FIG. 1 is similar to that of the conventional semiconductor laser device (1).

The above is yet another example of the conventionally proposed semiconductor laser device.

The semiconductor laser device having this configuration is the same as the conventional semiconductor laser device shown in FIG. 1 except for the matters mentioned above. As in the case of the device, the function as a semiconductor laser device can be obtained.

In addition, in the case of the conventional semiconductor laser device shown in FIG. 3, atoms 15 are introduced into the region below the conductive layer 9 of the semiconductor layer 3 to avoid lowering the energy band gap. The energy band gap of the region other than the region under the layer 9, that is, the region on the inter-fold end faces F1 and F2 side of the semiconductor layer 3 is relatively higher than that of the region of the semiconductor layer 3 under the conductive layer 9. Therefore, the light absorption coefficient of the region on the inter-fold end faces F1 and F2 side of the semiconductor layer 3 at the wavelength of the SEA 11 oscillation is relatively lower than the light absorption coefficient of other regions.

Therefore, in the case of the conventional semiconductor laser device shown in FIG.
It does not have the above-mentioned drawbacks of the conventional semiconductor laser device shown in FIG.

However, as shown in FIG. 3, in the case of the conventional semiconductor laser device, it is difficult to introduce atoms that avoid lowering the energy band gap into the region below the conductive layer 9 of the semiconductor layer 3, and for this reason, the semiconductor laser device However, there are drawbacks such as the inability to provide laser equipment at a low price.

Therefore, the present invention provides a novel ≧1'
- This will become clear from the detailed description below.

FIG. 4 shows an example of a semiconductor sheet 11 device according to the present invention.

In FIG. 4, parts corresponding to those in FIG. 1 are denoted by the same reference numerals and detailed explanations are omitted.

The semiconductor laser device according to the present invention shown in FIG. 4 has the same structure as the conventional semiconductor laser device shown in FIG. 1 except for the following points.

The semiconductor layer 3 forming the semiconductor stack 5 is the fifth
As shown in the figure, for example, single-crystal Ga is used as the mother-child well layer.
A semiconductor layer 21 having a thickness of ΔS and having a thickness of several thousand or less, and a barrier layer such as Δl, Ga, , Δ
A superlattice structure in which semiconductor layers 22 having Q<z<1> and having a thickness of 000 Å or less are sequentially stacked in multiple layers in an alternating manner.

Further, as in the case of the conventional semiconductor laser device shown in FIG.
Although it extends between the folds, the extension plane P of the plane V1 and the interfold end plane F1
1 and between the surface V2 and the extension surface P2 of the inter-fold end surface F2.

The above is an example of the configuration of a semiconductor laser device according to the present invention.

With such a configuration, it has the same configuration as the conventional semiconductor laser device shown in FIG. 1, except for the above-mentioned matters. Functions such as semiconductor relay mounting protection can be obtained.

However, in the case of the semiconductor laser device according to the JA invention shown in FIG. Since it does not extend between the parallel surface V1 and between the inter-fold end surface F2 and the inter-fold end surface F2 and the parallel surface V2, KiI71 NOA is injected into the inter-fold end surfaces F1 and F2 of the semiconductor layer 3. do not. However, the semiconductor layer 3h has a superlattice structure.

For this reason, according to FIG.
In the case of the device, the region 1 under the conductive layer 9 of the semiconductor layer 3 is covered with [ as in the case of the conventional semiconductor laser device shown in FIG.
Since no atoms are introduced to lower the energy bandgap, t' is also less than 17% of the semiconductor layer 3 at the wavelength of ray (f) oscillation.
The light absorption coefficient on the interfold end faces F1 and F2 is tJ\ compared to other regions.

Accordingly, the semiconductor laser device according to the present invention does not have the above-mentioned drawbacks of the conventional semiconductor laser device shown in FIG. In the case of the semiconductor laser device according to the present invention shown in FIG. 4, the semi-nine body layer 3 extends by 2C between the end faces F1 and C, whereas the conventional semiconductor laser device shown in FIG. The device does not have the drawbacks mentioned above in case tO).

Furthermore, in the case of the semiconductor device according to the invention as shown in FIG. 4, the semiconductor layer 3 has a superlattice structure. However, that! Semiconductor layer 2 constituting the rU lattice structure
1 and 22 to form the semiconductor layers 2 and 4,
It can be easily formed by epitaxy cell growth method.

Therefore, the semiconductor laser device according to the present invention shown in FIG. 4 has the great feature that it does not have the above-mentioned drawbacks of the conventional semiconductor laser device not shown in FIG.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are sectional views showing conventional semiconductor laser devices. FIG. 4 is a linear sectional view showing an example of a semiconductor laser device according to the present invention. FIG. 5 is an enlarged cross-sectional view along a line without showing the semiconductor layer as the active layer. 1... Semiconductor substrate 2
．． 3.4... Semiconductor layer 5... Semiconductor laminate Fl, F2... Male open end surface PI, P2... ...Extension surface 8,0...Conductivity↑! 1 layer V1. V
2... Surface 21. 22... Semiconductor layer Applicant 1 Telegraph and Telephone Corporation (Figure 2, Figure 4, Figure 5) 1

Claims (1)

[Claims] A first semiconductor layer having a first conductivity type as a first cladding layer on a semiconductor substrate having a first conductivity type;
a second semiconductor layer as an active layer; and a third semiconductor layer having a second conductivity type opposite to the first conductivity type as a second cladding layer.
semiconductor layers are stacked in that order, and the semiconductor stacks are parallel to each other and face each other.
and a second 93 open end surface, a first conductive layer serving as a first electrode is formed on the semiconductor substrate side surface of the semiconductor stack, and the third conductive layer of the semiconductor stack In a semiconductor laser device in which a second conductive layer is formed on a surface on the semiconductor layer side, the second semiconductor layer has a superlattice structure, and the second conductive layer has a superlattice structure. It extends between the first and second surfaces parallel to the first and second inter-fold end surfaces passing inside the inter-fold end surfaces of No. 2, but between the first surface and the first inter-fold end surface. A semiconductor laser device characterized in that there is no extension between the extension surface and the extension surface of the second surface and the second inter-fold end surface.