JPS6262582A - Buried semiconductor laser element - Google Patents

Abstract

PURPOSE:To readily form a CD-PBH structure by forming at least the edge at an acute angle near a mesa stripe of a parallel groove near a right angle, and forming the edge farther at an obtuse angle near a round. CONSTITUTION:An N-type InP layer 12, an InGaAsP active layer 13, a P-type InP layer 14 are sequentially grown on an N-type InP substrate 11, and double channels 15 are formed by PR and etching. At this time, the inside edge 16 of a mesa top side is formed at an acute angle near a right angle, the outside edge 17 is formed at an obtuse angle near a circle, and the channels 15 are buried by liquid-phase epitaxially growth. At this time, an N-type block layer 18 is not grown in mesa top 19 so as to be continued without disconnection at the portion except it. Since the angle of the edge 16 is acute, the grown layer is readily cut until the channels are almost buried, hardly grown on the mesa top, while since the edge 17 is obtuse, epitaxial layer is readily connected in and out of the channels. Thus, a DC-PBH structure can be readily obtained by altering the shape of the inside and outside edges of the double channels.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to optical fiber communications, and particularly to the structure of a DC-PBH type laser used for long-distance, high-capacity communications.

[Conventional technology]

Conventionally, this DC-PBH type laser configuration has been made by forming a double channel in a double hetero shrimp wafer and further embedding this channel in liquid phase shrimp. The shape of the double channel at this time was bilaterally symmetrical, with both the inner and outer edges forming an almost right-angled acute angle.

[Problem that the invention seeks to solve]

The shape of the conventional double channel described above is symmetrical, with both the inner edge and the outer edge having an acute angle close to a right angle, as shown in FIG. Liquid phase shrimp growth was performed on the substrate with this double channel structure, and the DC-PBH with the structure shown in Fig. 4 was developed.
Form a laser. At this time, a stain flow block layer is formed by growth, but this block layer must have a structure in which it does not grow on the mesa top but on the flat portion inside the channel and outside the double channel. However, in the conventional type shown in Figure 3, the inner and outer edges of the double channel are acute angles and have a symmetrical structure, so if conditions are chosen to prevent growth on the mesa top, both shoulders are likely to break. If you choose conditions that will make it easier to grow on the mesa top. When a block layer grows on the mesa top, the series resistance increases, making it difficult to operate as a laser. In the symmetrical double channel structure shown in Fig. 3, the DC-PBH structure shown in Fig. 4 is formed on the mesa top, which has a small area, compared to the flat area outside the double channel, which has a very wide area. This is because it is difficult to grow. As described above, a structure formed with a delicate balance has a disadvantage in that the production process capacity is low and stable production cannot be performed.

[Means for solving problems]

The semiconductor laser device of the present invention has a semiconductor wafer with a multilayer structure in which a semiconductor multilayer film including at least an active layer is laminated on a semiconductor substrate of a first conductivity type, and is sandwiched between two parallel grooves deeper than the active layer. In a buried heterostructure semiconductor laser formed by forming a mesa stripe and then growing it in a buried structure, at least the edge of the parallel grooves closer to the mesa stripe has an acute angle close to a right angle, and the edge farther away has an obtuse angle close to a circle. have.

〔Example〕 Next, the present invention will be explained with reference to the drawings.

1 and 2 are cross-sectional views of one embodiment of the present invention. Figure 1 is a cross-sectional view of where a double channel is formed, and the second
The figure is a cross-sectional view of nine places where buried growth is performed.

On the n-type InP sub 11, an n-type InP layer 12, In
GaAsP active layer 13. A P-type InP layer 14 is sequentially grown and PR and etched are performed to form a double channel 15. At this time, the inner edge 16 on the mesa top side is made into an acute angle close to a right angle, and the outer edge 17 is made into an obtuse angle close to a right angle. A double channel shaped as shown in Figure 1 is filled with liquid phase shrimp growth. At this time, the n-block layer 18 must not grow on the mesa top 19, but must continue unbroken at other locations. Since the corner of the edge 16 on the mesa top side is an acute angle close to a right angle, the growth layer is likely to break until the channel is almost filled, and it is difficult to grow on the mesa top.

- Since the outer edge 17 has an obtuse angle close to a circle, it is easy for the shrimp layer to spread inside and outside the channel. Therefore, by changing the shape of the inner and outer edges of the double channel, a C-PBH structure as shown in FIG. 2 can be easily obtained.

〔Effect of the invention〕

As explained above, the present invention makes the inner edge of the double channel an acute angle close to a right angle and the outer edge an obtuse angle close to a circle. It does not grow on the top of the mesa, but can grow uniformly without breaking in other parts,
This has the effect that a DC-PBH structure can be easily formed.

In the explanation of this embodiment, a DC-PBH structure using an n-type substrate was explained, but a DC-PBH structure using a p-type substrate was explained.
It is clear that the structure of the present invention also has a similar effect.

[Brief explanation of drawings]

FIGS. 1 and 2 are sectional views for explaining one embodiment of the present invention, and FIGS. 3 and 4 are sectional views for explaining a conventional technique. Here, Figures 1 and 3 are cross-sectional views of the area where the double channel was formed, and Figures 2 and 4 are views of the area where these double channel channels were embedded by liquid phase shrimp growth. . 11----InP substrate, 12----n type T,
nP layer, 13・----・InGaAsP active layer, 14
-・-P-type InPNj, 15...Double channel, 16...Inner edge, 17...
Outer edge, 18......n-type block layer, 19...
...Mesa top area.

Claims (1)

[Claims] A multilayer structure semiconductor wafer in which a semiconductor layer film including at least an active layer is laminated on a first conductivity type semiconductor substrate is formed with a mesa stripe sandwiched between two parallel grooves deeper than the active layer, and then embedded growth is performed. In the buried heterostructure semiconductor laser, at least the edge of the parallel grooves closer to the mesa stripe has an acute angle close to a right angle, and the edge farther away has an obtuse structure close to a circle. Semiconductor laser element.