JPH0927656A - Manufacture of ridge waveguide semiconductor laser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a ridge waveguide semiconductor laser which is low in threshold current and high in luminous efficacy. SOLUTION: An SiO2 mask 12 is formed on an N-InP substrate 11, and an etching process is carried out for the formation of a mesa stripe 11A. A high-resistance layer 13 is grown filling up each side of the mesa stripe 11A to be flush with the mesa stripe 11A. Then, the SiO2 mask 12 is removed, and then an N-InP clad layer 14, an active layer 15, a P-InP clad layer 16, and a P-InGaAsP contact, layer 17 are successively grown. Then, an SiO2 stripe mask is formed, and a ridge 18 is formed by etching. Next, an SiO2 insulating film 19 is formed on all the surface, and a window 19A is provided to only the top of the ridge 18, and a P-side electrode 20 is formed. An N-side electrode 21 is formed on the bottom of the N-InP substrate 11. By this setup, a high- resistance current, blocking layer is introduced under the active layer 15 of a ridge waveguide semiconductor laser.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ridge waveguide semiconductor laser used as a light source for optical communication.

[0002]

2. Description of the Related Art Conventionally, a ridge waveguide semiconductor laser of this type is, for example, a "Single-mode".
C. W. Ridge-waveguide Laser
Emitting at 1.55 μm ”I. P.
Kaminow, R.M. E. FIG. Nahory, M .; A. Po
Llack, L .; W. Sturz, and J.M. C. D
einter, Electronics Lette
rs Vol. 15 (1979) P.I. 763 to 765, which will be described below.

FIG. 2 is a sectional view of a conventional ridge waveguide semiconductor laser shown in the above document. As shown in this figure, on an n-InP substrate 1, an n-InP clad layer 2, an InGaAsP active layer 3, a p-InGaAsP buffer layer 4, a p-InP clad layer 5, a p-InGaA layer.
The sP cap layer 6 is grown.

Next, a mask with a width W for a ridge having openings (valleys) 10 with a width V at both ends is formed, and HCl + H ₃ P
The ridge 9 is formed by an etchant of O ₄ . At this time, the p-InGaAsP buffer layer 4 serves as an etching stop layer. Next, after depositing the SiO ₂ insulating film 7 on the entire surface by sputtering, a window is formed only in the ridge portion. Finally, the p-side electrode 8 is formed.

[0005]

However, in the above-mentioned conventional ridge waveguide semiconductor laser, the current injected from the electrode is near the active layer 3 because the current is not constricted below the active layer 3. , The threshold current value is high, and the luminous efficiency is poor. SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above problems and provide a method for manufacturing a ridge waveguide semiconductor laser having a low threshold current value and a high light emission efficiency.

[0006]

In order to achieve the above object, the present invention provides a method for manufacturing a ridge waveguide semiconductor laser, in which a mask is formed on a first conductivity type InP substrate and etching is performed to form a mesa stripe. A step of forming, a step of burying and flattening a high resistance layer on both sides of the mesa stripe, a first conductivity type InP clad layer, an active layer, a second conductivity type InP clad layer, and a second conductivity type In
A step of sequentially growing a GaAsP contact layer, a step of forming a stripe mask and forming a ridge by etching, and a step of forming an insulating film over the entire surface and then forming a window only above the ridge to form an electrode. It is something that is applied.

[0007]

According to the present invention, as described above, n-InP
A SiO ₂ mask is formed on the substrate and etching is performed to form a mesa stripe. A high resistance layer is embedded and grown on both sides of the mesa stripe to flatten the device.
Next, an n-InP clad layer, an active layer, and p-InP
A clad layer and a p-InGaAsP contact layer are sequentially grown. Next, a SiO ₂ stripe mask is formed, and a ridge is formed by etching. Next, SiO
₂ After forming an insulating film on the entire surface, a window is formed only on the ridge and an electrode is formed.

In this way, by introducing the high resistance current blocking layer below the active layer of the ridge waveguide semiconductor laser, the threshold current value can be reduced and the light emission efficiency can be improved.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of a manufacturing process of a ridge waveguide semiconductor laser showing an embodiment of the present invention. (1) First, as shown in FIG. 1A, a SiO ₂ mask 12 having a width W1 is formed on an n-InP substrate 11, and etching is performed to form a mesa stripe 11A. Here, it is better that the width W1 is narrower, but W2 [see FIG. 1 (d)]
Wider than.

(2) Next, as shown in FIG. 1B, high resistance layers 13 are buried and grown on both sides of the mesa stripe 11A to flatten the element. (3) Next, as shown in FIG. 1C, after removing the SiO ₂ mask 12, the n-InP clad layer 14, the active layer 15, the p-InP clad layer 16, and the p-InGaAs are formed.
The P contact layer 17 is grown.

(4) Next, an SiO ₂ stripe mask (not shown) having a width W2 is formed on the p-InGaAsP contact layer 17, and as shown in FIG. 1D, the ridge 18 having a width W2 is etched. To form. At this time, the width W2 is set to the horizontal mode. Next, SiO
_{2 The} insulating film 19 is formed on the entire surface. (5) Finally, as shown in FIG. 1E, after forming the window 19A only on the upper portion of the ridge 18, the p-side electrode 20 is formed, and the n-InP substrate 11 side is provided with the n-side electrode 21. Form.

Therefore, in FIG. 1E, when a bias is applied so that the p-side electrode 20 side of the ridge waveguide semiconductor laser becomes +, a current flows from the p-InGaAsP contact layer 17 toward the n-InP substrate 11. Flows and laser oscillation occurs. It should be noted that the present invention is not limited to the above embodiment, and various modifications can be made based on the gist of the present invention, and these are not excluded from the scope of the present invention.

[0013]

As described above in detail, according to the present invention, in the ridge waveguide semiconductor laser,
By introducing the high resistance current blocking layer below the active layer, it is possible to reduce the threshold current value and improve the luminous efficiency.

[Brief description of drawings]

FIG. 1 is a sectional view of a ridge waveguide semiconductor laser manufacturing process showing an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional ridge waveguide semiconductor laser.

[Explanation of symbols]

11 n-InP substrate 11A Mesa stripe 12 SiO ₂ mask 13 High resistance layer 14 n-InP clad layer 15 Active layer 16 p-InP clad layer 17 p-InGaAsP contact layer 18 Ridge 19 SiO ₂ insulating film 19A window 20 p-side electrode 21 n-side electrode

Continuation of the front page (72) Inventor Hiroki Yaegashi 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd.

Claims (1)

[Claims] 1. A method for manufacturing a ridge waveguide semiconductor laser, comprising: (a) a step of forming a mask on a first conductivity type InP substrate and performing etching to form a mesa stripe; and (b) both sides of the mesa stripe. And a step of (c) sequentially growing a first conductivity type InP clad layer, an active layer, a second conductivity type InP clad layer, and a second conductivity type InGaAsP contact layer. , (D) forming a stripe mask and forming a ridge by etching, and (e) forming an insulating film over the entire surface and then forming a window only above the ridge to form an electrode. A method of manufacturing a ridge waveguide semiconductor laser having a feature.