JPH01316985A - Generation of semiconductor laser - Google Patents

Abstract

PURPOSE:To decrease a leakage current so as to obtain a semiconductor laser capable of operating at a high speed by a method wherein a process is performed without exposing an active layer to air so as to prevent an n-growth layer from forming beside an active later region. CONSTITUTION:A mask pattern 13 is provided onto an n-type InP clad layer 10, an InGaAsP active layer 11, and a first P-type InP clad layer 12 which have been laminated, which is subjected to a laboratory etching and then a semi-insulating current blocking layer 14 is grown inside and over the etched groove. The pattern 13 is removed and a dielectric insulating film 16 pattern formed of SiO2 is provided in place of it, and a Zn doped second P-type clad layer 15 is grown until the upside of an element becomes even. Lastly, electrodes 17 and 18 are provided to both the front and rear of the element. By these processes, a leakage current can be decreased and a semiconductor laser operable at a high speed can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing a semiconductor laser used for optical communications and optical information processing, and more particularly to the formation of a semi-insulating current blocking layer.

(Prior Art and its Problems) Semiconductor lasers are key devices in optical communications and optical information processing, and are required to have low reactive leakage current, operate at high speed, and be easy to manufacture.

Semiconductor lasers in which semi-insulating current blocking layers are embedded on both sides of the active region are expected to meet the demands for low reactive leakage current, high speed operation, and easy manufacturing.

A conventional example of such a semiconductor laser is described in Electronics Letters, Vol. 22, 1986, p. 1214 (Electr.
on, Lett, gλ1214 (1986)). FIG. 2 is a schematic process diagram of a conventional manufacturing method for this element. That is, as shown in FIG. 2(I), n
InP type cladding layer 10. InGaAsP active layer 11
In the first step, a striped mask pattern 13 is formed on a double heterostructure wafer sample consisting of a p-type InP cladding layer and etched to form a mesa-shaped active region.
and a second step of embedding semi-insulating current blocking layers 14 on both sides of the active region by vapor phase growth as shown in FIG. 2(II). With this conventional device manufacturing method, it is not easy to always produce devices with a predetermined active region width and a small leakage current on both sides of the active region.

That is, in the conventional manufacturing method, since the thickness of the p-type rad layer 12 is large, it is not necessarily easy to control the dimensions by etching in the first step. In addition, in the conventional method, the first
Since both sides of the active region are exposed to the atmosphere after the second step until the second step, there is a problem in that a metamorphosed layer is formed and a large leakage current is generated due to surface recombination current. In addition, to avoid this, in the laboratory (in-house) inside the growth reactor.
5) Although attempts have been made to grow the buried layer 14 using etching or meltback,
At this time, there was a problem that the dimensional control of the active region width became even worse.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor laser that eliminates the problems in the conventional device manufacturing method described above, has low leakage current, is fast, and allows easy control of the width of the active region.

(Means for Solving the Problems) In the method for manufacturing a semiconductor laser of the present invention, the active layer has an
A striped mask pattern is provided on a wafer sample having a structure in which a p-type semiconductor cladding layer is sandwiched between a first p-type semiconductor cladding layer on the upper side, and a striped mask pattern is provided in a laboratory (in-house) up to the active layer directly under the mask pattern. 5itu) A first step of growing a semi-insulating current blocking layer in and on the etching groove immediately after etching, and a second step of growing a semi-insulating current blocking layer on the first p-type semiconductor cladding layer from which the mask pattern has been removed. It is characterized by having a second step of selectively growing a p-type semiconductor cladding layer to form a mesa-shaped current carrying part.

(Operation of the invention) The operation of the invention will be explained using the drawings, taking an InGaAsP/InP laser as an example. In the present invention, first, the first
N-type InP cladding layer 10 stacked as shown in Figure (Ia)
A mask pattern 13 is provided on the InGaAsP active layer 11 and the first p-type InP cladding layer 12.
Immediately after etching (I
As in b), a semi-insulating current blocking layer 14 is grown in and on the etched trench. In the present invention, a first p-type InP7 rad layer 12 was provided with a thickness sufficient to allow control of the width of the active region after etching using a mask pattern without exposing the active layer 11. In the room (in 5
By performing the etching process, the width of the active region can be controlled well and leakage current due to the surface recombination mechanism on both sides of the active layer can be reduced. In addition, in the growth of semi-insulating current blocking layers, conventional vapor phase epitaxy (VPE) is used.
(method), n-growth 21 grows beside the active region, and electrode 17
Although there was also a leakage current flowing directly from the n-type rad layer IO to the n-type rad layer 21, the present invention can also prevent leakage current due to this mechanism.

Examples of the present invention will be described in more detail below.

(Example 1) FIG. 1 is a process schematic diagram showing an example of the present invention. In the present invention, as shown in FIG. 1 (Ia), sulfur (S) is
0.1 pm thick InG with wavelength 1.3 pm composition on n-type InP cladding layer 10 doped to 0.018 cm
aAsP active layer 11 and zinc (Zn) of about 2×1018
cm-3 doped 0.211 m thick first p-type I
An 8102 mask pattern with a stripe width of about 1.5 pm was provided on the wafer sample on which the nP cladding layer 12 was grown. This sample was placed in a vapor phase epitaxy (VPE) furnace in an InCl and P gas atmosphere used for normal InP growth, and HCI etching gas was passed through it, and the portion not covered by the mask pattern was injected in 5 it up to the lower end of the active layer 11.
U-etching was performed. Immediately thereafter, the supply of MCI etching gas is stopped, and FeCl2 gas is fed instead to grow a semi-insulating current blocking layer 14 made of Fe-doped InP with a thickness of 3 m as shown in FIG. 1 (Ib). The process was carried out. Subsequently, as a second step, a mesa-shaped current carrying portion consisting of a second p-type InP cladding layer was formed. That is, as shown in FIG. 1 (II), instead of removing the mask pattern 13, a dielectric insulating film 16 pattern made of SiO2 is provided, and about 2×10
A second p-type InP cladding layer doped with 18 cm-3 was grown until the top surface of the device was flat. Finally, a semiconductor laser was manufactured through the usual process of providing electrodes 17 and 18 on the front and back screens of the device.

In the present invention, there is almost no n-growth layer compared to the conventional manufacturing method, and oscillation can be achieved with a low current value. Furthermore, it was confirmed that the active region width was uniform and had good reproducibility as a predetermined value.

In this embodiment, a case has been described in which the first p-type rad layer and the second p-type rad layer have the same doping and the same composition, but they are not necessarily limited to the same doping or the same composition.

Furthermore, although the VPE method is used in this embodiment, metal organic chemical vapor deposition (MOCVD), gas source molecular beam growth, or the like may also be used.

(Effects of the Invention) According to the present invention, the process can be performed without exposing the active layer to the atmosphere, and since no n-growth layer is formed next to the active layer region, the leakage current is smaller and the manufacturing speed is faster than in the conventional manufacturing method. Accordingly, it is possible to manufacture a semiconductor laser that operates at a high temperature and whose active region width can be easily controlled.

[Brief explanation of the drawing]

FIG. 1 is a schematic process diagram of a semiconductor laser manufacturing method according to the present invention, and FIG. 2 is a process schematic diagram of a conventional semiconductor laser manufacturing method. 10... n-type semiconductor cladding layer, 11... active layer,
12... First p-type semiconductor cladding layer, 13... Mask pattern, 14... Semi-insulating current blocking layer, 15...
...Second p-type semiconductor cladding layer, 16...Dielectric insulating film, 17.18...Electrode, 21...N- growth layer

Claims (1)

[Claims] Manufacturing a semiconductor laser having a structure in which an active layer is sandwiched between an n-type semiconductor cladding layer on the lower side and a first p-type semiconductor cladding layer on the upper side, and both sides of the active layer are buried in semi-insulating current blocking layers. In the method, a striped mask pattern is provided on a first p-type semiconductor cladding layer, and the active layer directly under the mask pattern is in situ.
A first step of growing a semi-insulating current blocking layer in and on the etched groove immediately after etching, and a second step of growing a semi-insulating current blocking layer on the first p-type semiconductor cladding layer from which the mask pattern has been removed. 1. A method of manufacturing a semiconductor laser, comprising a second step of selectively growing a semiconductor cladding layer to form a mesa-shaped current carrying part.