JPH05251822A - Manufacture of semiconductor laser element - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a high-efficiency and high- output semiconductor laser element, wherein the filling of an active layer is performed utilizing well a selective growth property due to a difference in the face orientation properties of layers, light confinement waveguides are respectively formed at both ends of the active layer and a reduction in a threshold current can be achieved and which is excellent in current injection efficiency and has little leakage current. CONSTITUTION:An N-type InP blocking layer 22 and a P-type InP blocking layer 23 are formed by a liquid growth process in order on a P-type InP substrate 21, a V-shaped groove is formed by etching using a hydrochloric acid etchant and a thick P-type InP clad layer 24, a thin P-type InGaAsP layer 25, a thin P-type InGaAsP active layer 26, a thin N-type InGaAsP layer 27 and a thick N-type InP clad layer 28 are liquid-phase grown in order on the lower part of the V-shaped groove to fill the V-shaped groove.

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 an embedded semiconductor laser device used for long-distance optical communication, optical measuring instruments, optical amplifiers and the like.

[0002]

2. Description of the Related Art Conventionally, as a technique in such a field,
For example, "High Power Long Wave
length Laser Diode "Y. KAW
AI, A. MATOBA, OKI Technical
Review, 124, Vol. 52, P.I. 62-6
8 were described.

FIG. 3 is a sectional view of a manufacturing process of such a conventional semiconductor laser device. The conventional method of manufacturing the semiconductor laser device will be described below. First, as shown in FIG. 3A, a p-InP buffer layer 2, an n-InP block layer 3, and a p-InP block layer 4 are sequentially grown on a p-InP substrate 1 in a liquid phase. Next, as shown in FIG. 3B, the V groove 5 is formed by etching with a hydrochloric acid-based etchant.

Next, as shown in FIG. 3C, p-I
nP clad layer 6, InGaAsP active layer 7, n-In
P clad layer 8, n-InGaAsP contact layer 9,
The n-InP protective layer 10 is sequentially grown in liquid phase. As described above, the DH (Do) in which the InGaAsP active layer 7 is sandwiched between the InP cladding layers 6 and 8 having a larger gap than that.
A laser diode having a double-hetero structure has a PNPN current blocking portion and has a structure in which a current is efficiently injected into an active layer.

[0005]

However, the above-mentioned conventional semiconductor laser device, that is, the VIPS-LD is used.
(V-grooved Inner-stripe o
n P-InP Substrate Laser D
In iodes), since the active layer has a simple DH structure, a sufficiently low threshold current cannot be achieved.

A double heterostructure having an optical guide layer having a composition having an energy gap larger than that of a carrier confinement layer, a so-called SCH (Sepa).
A laser diode having a rate confinement hetero structure has also been proposed, but the laser diode having this SCH structure has a problem of a large leak current.

According to the present invention, the above problems are eliminated, the active layer is embedded by making good use of the selective growth property due to the difference in plane orientation, and the optical confinement waveguide is formed at both ends of the active layer. Threshold current can be achieved, current injection efficiency is good,
It is an object of the present invention to provide a method of manufacturing a semiconductor laser device having high efficiency and high output with a small leak current.

[0008]

In order to achieve the above-mentioned object, the present invention provides a method for manufacturing a semiconductor laser device in which an active layer is embedded by using a selective growth property by a liquid phase growth method,
A PNP block layer is formed on a conductor substrate, a V groove is formed by etching, a P-type thick first clad layer is formed under the V groove, and a thin P-type clad layer is formed on the first clad layer. Forming a second clad layer, forming a thin N-type active layer on the second clad layer, forming a thin N-type third clad layer on the active layer; A thick N-type fourth cladding layer is formed on the cladding layer so as to fill the V groove.

[0009]

According to the present invention, as shown in FIG. 1, p-In
On the P substrate 21, n-InP block layer 22, p-In
The P block layer 23 is sequentially grown in a liquid phase, and a V groove is formed by etching with a hydrochloric acid-based etchant. A thick P type InP clad layer 24 and a thin P type InGaA are formed under the V groove.
Since the sP layer 25, the thin P-type InGaAsP active layer 26, the thin N-type InGaAsP layer 27, and the thick N-type InP clad layer 28 are sequentially liquid-phase-grown to fill the V-groove, the plane orientation may vary. A semiconductor laser device in which an active layer is buried by making good use of selective growth properties, and optical confinement waveguides are formed at both ends of the active layer to achieve a low threshold current, good current injection efficiency, and low leakage current. Can be obtained.

Further, since the withstand voltage of the current block layer formed on the semiconductor substrate is high, current can be efficiently injected into the active layer even in a high current region, and high-power laser oscillation becomes possible, resulting in high efficiency and high efficiency. An output semiconductor laser device can be obtained.

[0011]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a sectional view of a main part of a semiconductor laser device showing an embodiment of the present invention. The method of manufacturing the semiconductor laser device will be described below. First, on the semiconductor substrate, the p-InP substrate 21, the n-InP block layer 22,
The p-InP block layer 23 is sequentially grown in liquid phase. Next, a V groove is formed by etching with a hydrochloric acid-based etchant, and a thick p-InP clad layer 24 is formed under the V groove.
Thin p-InGaAsP cladding layer 25, thin p-In
A GaAsP active layer 26, a thin p-InGaAsP cladding layer 27, and a thick n-InP cladding layer 28 are sequentially grown in a liquid phase so as to fill the V groove. here,
The band gap may be selected to be appropriately larger than that of the InGaAsP active layer 26. Since it is necessary to form a thin (thickness d ≦ 0.05 μm) epitaxial growth layer for the InGaAsP active layer 26, the InGaAsP active layer 26 is formed by a method of using a melt box as shown in FIG. To do.

Hereinafter, this point will be described in detail with reference to FIG. In FIG. 2, 30 is an InP substrate,
31 is a slide board, 32 is a push rod, 33 is a melt box, 34 is a board body, 41 is p-InP
Solution, 42 is p-InGaAsP solution, 43 is p-In
GaAsP solution, 44 is n-InGaAsP solution, 45
Is an n-InP solution.

As shown in this figure, the slide board 31
The InP substrate 30 having the V groove formed thereon is
-InP solution 41 is brought into contact to form a thick P-type InP clad layer 24 (see FIG. 1). Here, p-In
Since the P solution 41 is contained in the solution reservoir in which the width d ₁ of the melt box 33 is considerably wide, the thick P-type InP clad layer 24 can be formed.

Next, p-InGaAsP (λg = 1.2)
μm) contacting the solution 42, thin p-InGaAsP
The clad layer 25 (see FIG. 1) is formed. Here, p
-InGaAsP solution 42 has a width d of the melt box 33
_{Since 2} is stored in a fairly narrow solution reservoir, a thin p
-InGaAsP clad layer 25 can be formed.

Next, p-InGaAsP (λg = 1.1)
μm) Solution 43 is brought into contact with thin p-InGaAsP
The active layer 26 (see FIG. 1) is formed. Here, p-I
Since the nGaAsP solution 43 is contained in the solution reservoir having the narrowest width d ₃ of the melt box 33, a thin p-In solution is used.
The GaAsP active layer 26 can be formed. next,
The thin n-InGaAsP cladding layer 27 (see FIG. 1) is formed by bringing the n-InGaAsP (λg = 1.2 μm) solution 44 into contact therewith. Here, since the n-InGaAsP solution 44 is contained in the solution reservoir in which the width d ₄ of the melt box 33 is considerably narrow, the thin n-InGaAsP cladding layer 27 can be formed.

Next, the n-InP solution 45 is contacted,
A thick N-type InP clad layer 28 (see FIG. 1) is formed. Here, the n-InP solution 45 is melted in the melt box 3
Since the width d _{5 of} 3 is accommodated in a solution reservoir having a considerably large width, a thick P-type InP clad layer 28 can be formed. In this way, a thin (thickness d ≦ 0.05 μm) epitaxial growth layer can be formed for the InGaAsP active layer 26.

By adopting such a structure of the semiconductor laser device, the threshold value is lower than that of the ordinary VIPS-LD, and the SCH
A semiconductor laser device (laser diode) with less current leakage than an LD can be manufactured. It should be noted that the present invention is not limited to the above embodiments, and various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

[0018]

As described above in detail, according to the present invention, as described above, the PNP block layer is formed on the conductor substrate, the V groove is formed by etching, and the V groove is formed below the V groove. Forming a P-type thick first clad layer, and forming a thin P-type second clad layer on the first clad layer;
A thin N-type active layer is formed on the second clad layer, a thin N-type third clad layer is formed on the active layer, and a thick N-type fourth layer is formed on the third clad layer. Since a clad layer was formed to fill the V groove,
A semiconductor laser device (laser diode) having a lower threshold than S-LD and less current leakage than BH-SCH-LD can be manufactured.

Further, since the current blocking layer formed on the semiconductor substrate has a high withstand voltage, current can be efficiently injected into the active layer even in a high current region, and high-power laser oscillation becomes possible, resulting in high efficiency and high efficiency. An output semiconductor laser device can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a semiconductor laser device showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a melt box for liquid phase growth used for manufacturing a semiconductor laser device showing an example of the present invention.

FIG. 3 is a cross-sectional view of manufacturing steps of a conventional semiconductor laser device.

[Explanation of symbols]

 21 p-InP substrate 22 n-InP block layer 23 p-InP block layer 24 p-InP clad layer 25 p-InGaAsP clad layer 26 p-InGaAsP active layer 27 n-InGaAsP clad layer 28 n-InP clad layer 30 InP substrate 31 Slide Board 32 Push Rod 33 Melt Box 34 Board Body 41 p-InP Solution 42 p-InGaAsP Solution 43 p-InGaAsP Solution 44 n-InGaAsP Solution 45 n-InP Solution

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor laser device in which an active layer is embedded by using a selective growth property by a liquid phase growth method, comprising: (a) forming a PNP block layer on a semiconductor substrate; and (b) forming a V groove by etching. (C) forming a P-type thick first clad layer under the V-groove, and (d) forming a thin P-type second clad layer on the first clad layer, e) forming a thin N-type active layer on the second cladding layer, (f) forming a thin N-type third cladding layer on the active layer, (g) the third cladding A method of manufacturing a semiconductor laser device, characterized in that a thick N-type fourth cladding layer is formed on the layer to fill the V groove. 2. The first and fourth cladding layers are InP
2. The method for manufacturing a semiconductor laser device according to claim 1, wherein the second and third cladding layers are InGaAsP, and the active layer is InGaAsP.