JPS62143489A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To easily form a current blocking layer with sufficient controllability, in the deep part of crystal layer, by performing ion implantation in a buried- growth layer to form a current blocking layer after a mesa containing an active layer is buried with the same conduction type layer and is grown. CONSTITUTION:After an InGaAsP active layer and a P-type InP clad layer 6 are grown on an N-type InP substrate, a whole part is eliminated by etching, while the active layer of 0.5-2mum thick is left thereon. Then the whole part containing a mesa is buried with a P-type InP layer, and an InGaAsP cap layer is grown on its surface. Ion implantation of S, Se or Si is performed excepting the part to be a current path, and an N-type InP layer is formed by an annealing treatment. Comparing with a burying structure wherein a P-type layer and an N-type layer are selectively grown on the both sides of a mesa in the time of buried-growth, a current blocking layer can be easily formed thereby. It is also easily achieved to form an N-type layer in a P-type layer applying ion implantation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a buried semiconductor laser, and particularly to one suitable for introducing a manufacturing method with good controllability.

[Background of the invention]

In a buried structure semiconductor laser in which an active layer is formed in the first growth, the outside of the current flow path is removed, and the surrounding area is buried and grown, including a current blocking layer, p-type, n-type, and It is necessary to selectively grow a type current blocking layer, but at this time there were problems in controlling the growth shape and thickness of each layer6 (Kitamura et al., 1985 IEICE Semiconductor and Materials Division National Conference Proceedings, Vol. (See number 314).

[Purpose of the invention]

The purpose of the present invention is to obtain a current blocking layer of a buried structure laser by using selective growth and ion implantation method.
An object of the present invention is to provide a buried semiconductor laser in which a current blocking layer is formed with good controllability and is capable of high temperature and high output operation.

[Summary of the invention]

In order to achieve this object, after a mesa including an active layer is buried and grown with a layer of the same conductivity type, ions may be implanted into the buried growth layer to form a current blocking layer. Especially IM
By performing high-energy ion implantation of eV or higher, a current blocking layer can be easily formed at a deep position within the crystal layer with good controllability.

[Embodiments of the invention]

The present invention will be explained in detail below.

Example 1 An example of the present invention will be described with reference to FIG. In FIG. 1, 1 is an n-type InP substrate, 2 is a p-type InP buried growth layer, and 3 is S (ion), Ss (selenium), or Si.
An n-type layer (nP layer) formed in the p-type InP layer 2 by annealing after (silicon) ion implantation; 4 is an InP layer;
A GaAsP cap layer, 5 an active layer, and 6 a P-type InP cladding layer. The laser structure shown in this example first consists of an InGaAsP active layer, a p-type nP layer, and an InGaAsP active layer on an n-type InP substrate.
After growing the cladding layer 6, the active layer width is 0.5 to 2 μm and the other parts are removed by etching, the entire area including the mesa is buried with a p-type nP layer, and the surface is covered with InGaAsP.
Grow the cap layer, S except for the part that will become the current flow path,
It is obtained by forming an n-type layer nP layer by performing Ss or SL ion implantation and annealing.

According to this embodiment, the current blocking layer can be formed more easily than in the conventional implanted structure in which both Psn type layers are selectively grown on both sides of the mesa during buried growth. Furthermore, by using ion implantation, it was possible to easily form an n-type layer in a p-type layer, which was difficult to do using conventional diffusion methods.

In this example, the thickness of the n-type layer is at least 1
It is desirable that the thickness be µm or more. This is because the distance between the active layer and the surface layer is 1.5 .mu.m or more, and in addition, the connection between the two layers is 0.5 .mu.m or less in order to obtain a sufficient current confinement effect. The reason why the distance between the active layer and the surface layer is set to 1.5 μm or more is to avoid shortening the life of the laser due to stress caused by electrodes formed on the surface layer or the influence of metal diffusion.

For this purpose, when implanting SL ions into InP, approximately I
It is necessary to perform ion implantation at high energy of M e V or higher.

Although this embodiment shows a structure using an n-type substrate, similar effects can be obtained using a p-type substrate. In this case, the conductivity types of each layer shown in FIG. 1 are opposite to each other. In addition, the ions to be implanted into layer 3, which will become a p-type layer, include Zn, Cd, and Be.
, Mg, etc. are used.

In addition, although this example describes an InGaAsP laser on an InP substrate, an AZG laser on a GaAs substrate
It can be similarly used for an aAs-based laser or an (As)-based laser on a GaAs substrate.

Embodiment 2 FIG. 2 shows an embodiment of a laser structure according to the present invention. 1
The layers and the manufacturing method in Examples 1 to 6 are the same as in Example 1. The difference is that by adjusting the carrier density of the p-type layer nP layer of layer 2, the dose of the n-type layer nP layer by ion implantation of layer 3, and the implantation energy, the n-type layer nP J
? ? 3 is formed in the form of an island within the P-type layer nP layer 2. - For example, 2.7 M Si in the p-type layer nP
When implanted at eV, an impurity distribution having a peak near a depth of 2 μm is obtained. The dose is I x 10” at
Figure 3 shows the unconstrained concentration distribution when om/d. The carrier concentration of the P-type layer nP layer 2 is 5 x 1017 cm-”
When this is done, the region with a depth of 1.7 to 2.3 μm is inverted to the n-layer, and an island-shaped n-type layer n P M 3 is obtained. At this time,
In order to obtain a sufficient current confinement effect, it is desirable that the active layer 5 and layer 3 do not contact each other, and in addition, the distance between the active layer 5 and layer 3 is 1 μm or less. Further, in order to provide the current blocking layer with a sufficient voltage of 1, the thickness of the layer 3 is desirably 0.5 μm or more. According to this embodiment, a similar structure can be easily obtained without performing selective buried growth, and a laser capable of high-temperature, high-output operation can be easily formed.

Note that, like in Example 1, this embodiment uses a semiconductor laser having a p-type InP substrate, a GaAs substrate, etc.
-It can be used in general buried type semiconductor lasers having group compound or mixed crystal substrates.

〔Effect of the invention〕

According to the present invention, in a buried semiconductor laser, it is possible to selectively grow a Pan layer on both sides of a mesa to a thickness of 1 μm.
A current confinement layer having a narrow current flow path of 3 μm or less at the above depth can be easily formed, and a current confinement layer with good uniformity and high breakdown voltage can be obtained over the entire wafer surface. Therefore, according to the present invention, the dispersion of the threshold current and the breakdown voltage of the current blocking layer within the wafer can be reduced by 20% or more.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the laser structure, FIG. 2 is a sectional view of the laser structure, and FIG. 3 is a diagram showing the relationship between impurity concentration and depth when Si is implanted into an InP layer. 1... n-type InP substrate, 2... p-type layer nP layer, 3...
... n-type layer nP layer formed by ion implantation, 4.
...InGaAsP cap layer, 5-InGaAsP active layer, 6-p 1st (2) Stone 2 Figure

Claims (1)

[Claims] 1. In a buried semiconductor laser in which the active layer is surrounded by a crystal whose refractive index is smaller than that of the active layer, a current blocking layer is formed by forming a semiconductor layer in the crystal by ion implantation. A semiconductor laser characterized by having a Pm junction. 2. The semiconductor laser according to claim 1, wherein the ion implantation method is a high energy ion implantation method of 1 MeV or more to form a Pm junction in a deep crystal of 1 μm or more. 3. The semiconductor laser according to claim 1 or 2, wherein the semiconductor layer formed by the ion implantation method is formed in the form of an island in the crystal.