JPS62245693A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To perform a stable and high-output laser oscillation by a method wherein the substrate rear surface of a laser of a double hetero structure is formed into a stripe form to inhibit the lateral spreading of current and the threshold current is lowered. CONSTITUTION:An N-type GaAs buffer layer 2, an N-type AlGaAs clad layer 3, a GaAs active layer 4, a P-type AlGaAs clad layer 5 and a P-type GaAs cap layer 6 are epitaxially grown on an N-type GaAs substrte 1. A substrate rear surface 11 is subjected to inverse mesa etching and an SiO2 film 7 is deposited on the etched-away parts. The substrate regions held by the SiO2 films 7 are etched away. An SiO2 film 10 is formed on the cap layer 6, an Au-Cu alloy P electrode 8 is attached thereon and an Au-Ge-Ni alloy electrode 9 is attached on the substrate side. Lastly, a cleavage is performed to complete a laser. By this constitution, a stable and high-output laser oscillation can be performed by the use of a low-threshold current.

Description

[Detailed description of the invention] [Industrial application field] The present invention provides a semiconductor radar 9 having a double heterostructure. This invention relates to the stripe structure of the substrate.

[Conventional technology]

Conventionally, as shown in FIG. 1 described in Japanese Unexamined Patent Publication No. 57-49291 and FIG. However, in the prior art, the current injected from the electrode on the growing film side spreads and diffuses in the lateral direction before reaching the electrode on the substrate side. As a result, the threshold current increases, causing problems such as deviations and kinks in the linearity of the laser's optical output current characteristics, and the dependence of the laser beam radiation angle on the injection current. Ta.

The present invention is intended to solve these problems, and its purpose is to suppress the horizontal spread of current by forming stripes on the back surface of the substrate, lowering the final value current, and achieving stable and high output. It is what makes laser oscillation possible.

[Means to solve the problem]

A semiconductor laser according to the present invention, a semiconductor laser having a double heterostructure, characterized in that the back surface of the substrate of the semiconductor laser has a stripe structure [Embodiment] A detailed description of the present invention will be given below based on the drawings. do. FIG. 1 is a sectional view showing an example of a semiconductor laser having a double heterostructure according to the present invention.
It has 8 double heterozygosity. In the same figure, the outer mold (on the MLk8 substrate 1, an n-type transparent buffer layer'
2. n-type a side A8 cladding layer 3, side 8 active layer 4. Lp
A type MGIZ A, 9 cladding layer 5, and a p-type bag U cap layer 6 are formed in this order. The p-electrode 8 is the p-type Ga A8
It can be removed by sputtering or the like on the SiO2 selectively deposited on the drying layer 6 to block current. After etching the back surface of the n'm-A8 substrate 1 into an inverted mesa shape and depositing sj O2 to cut off the current, the remaining n-type ()a A8 substrate 1 was etched. , and then attached using a vapor deposition method or the like.

The details of the manufacturing method will be explained based on FIG. 2.

The current injected from the T electrode 8 flows from the stripe portion made of 5i0210 and reaches the stripe portion made of BiO27 and the n electrode 9.

The width of both stripes is made as small as about 2 μm to about 20 μm. As a result of the current h''- flowing through both the strike-to-wave parts,
Even in the active layer, diffusion of injected carriers to regions outside the stripe is suppressed, so that the threshold current can be reduced.

The manufacturing process of the semiconductor laser shown in FIG. 1 will be explained based on FIG. 2. The same symbols are used for the same parts as in FIG. Figure 2 (α) is -? On the L type L3a k8 substrate 1, sequentially nfJσAll buffer layer 2%, type aGa
A & cladding layer 3, A8 active Wi4, p-type Atshin A8
It is a sectional view after epitaxially growing a cladding layer 5 and a cap layer 6 on the p-type side. Next, in order to create a portion 5i027 shown in FIG. 2(b), the back surface 11 of the substrate is etched into a reverse mesa, and the etched portion
Deposit 7. After that, as shown in FIG. 2(C),
The substrate region sandwiched between the jO□7 is removed by etching. On the other hand, the grown film side has pFj as shown in Figure 2(d).
EliO210 is selectively deposited on the JJaaAttv-YAP layer 6 by CVD method etc., and the p electrode 8 is made of Au-OK.
It can be removed using vapor deposition methods such as The substrate side electrode is Au-Ge
−? : Gold alloy is attached by vapor deposition. Finally, a semiconductor laser as shown in FIG. 1 is created by the interosseous structure.

FIG. 3 shows another embodiment of the invention. The difference from FIG. 1 is the etching process of the substrate.

In Fig. 1, part h; of E3 f; 027;
mGa 1g substrate 31, and the n-type kA
, 9 The back surface of the substrate 31 has a striped structure. In this example as well, since the injection current flows between the stripes of both electrodes,
Diffusion of injected carriers in the active layer to regions outside the stripe is suppressed, and the threshold current can be reduced.

FIG. 4 shows yet another embodiment of the invention. p-type-A8
On the substrate 41, an nFJ true M buffer layer 42, an n-type uGa
As cladding layer 43, (MAJ active layer 44, p-type 1v
l (hZ A8 cladding layer 45 and P type (mkB cap layer 46 are formed in sequence.
It is made in the same way as the electrode 8 side, and the n electrode 49 side is made of p-type G.
4 Etch the At substrate 41 as shown in FIG.
After forming an n-type diffusion region 50 by ion implantation or the like, an n-electrode 49 is attached by vapor deposition.

The embodiments of the semiconductor laser of the present invention have been described above, but the claims relate to the stripe structure on the substrate side, and the electrode structure on the growth film side is not limited to the electrode stripe structure shown in the embodiments. It can also be applied to other stripe structures such as V-groove stripes, diffused stripes, etc., and there is no need for stripes.

In addition, in the example, description was made using 侃AJ/gaaA8-based materials, but
Other semiconductor crystal materials can also be used, such as those containing Sue&Tg or other light emitting materials.

〔Effect of the invention〕

As described above, according to the present invention, by forming the substrate side electrode or the back surface of the substrate into a striped structure, the spread of the injected current in the lateral direction is suppressed, the threshold current is lowered, and stable and high output is achieved. It can enable laser oscillation. Furthermore, conventionally, the electrode on the growth layer side near the active layer was glued to the heat sink.
The heat generated near the active layer is released to extend the life of the laser beam. A brazing material such as In or kg-EJn was used as an adhesive, but the brazing material adhered to the laser emitting end face, resulting in defective products. However, in the semiconductor laser of the present invention, the distance between the striped part of the electrode on the substrate side and the active layer is not much different from the distance from the electrode on the growth layer side to the active layer, so the electrode on the substrate side is bonded to the heat sink. Also, sufficient heat dissipation effect can be obtained.

At this time, since the heat sink adhesive surface can be the electrode end on the substrate side, the proportion of the brazing material adhering to the laser emitting end face is reduced and the yield is increased. Further, by sandwiching both electrodes between two heat sinks, the cooling effect can be enhanced and a higher output laser can be oscillated.As described above, the practical effects of the present invention are extremely large.

[Brief explanation of drawings]

FIG. 1 is an m-plane view showing an embodiment of a semiconductor laser according to the present invention. FIG. 2 is a manufacturing process diagram showing the manufacturing process of the semiconductor laser shown in FIG. 1. FIG. 3 is a dynamic view showing a semiconductor laser according to an embodiment of the present invention, which is different from that shown in FIG. FIG. 4 shows a semiconductor laser according to the present invention, and FIG. FIG. 4 is a sectional view showing a different embodiment from FIG. 3; 7...si o2 8...p electrode 9...n electrode 11...substrate back side 31...nu paddle A8 board 38... ...p electrode 39...n electrode 41...pfJ A8 board 48...pt electrode 49...n electrode and above Applicant: Seiko Epson Co., Ltd. Figure 2 Figure 41!1

Claims (1)

[Claims] A semiconductor laser having a plurality of layers of semiconductor thin films on a semiconductor substrate, and having electrodes on the back surface of the semiconductor substrate and on the semiconductor thin film, characterized in that at least the back surface of the semiconductor substrate or the electrodes on the semiconductor substrate side have stripes. semiconductor laser.