JPS61228693A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To prevent leaking currents from a current stripe layer in a semiconductor laser, by continuously providing a super lattice layer comprising a BaxCa1-xF2 layer and an InP layer, on both side surfaces of a current stripe layer including an active layer, which undergoes mesa etching, and on the surface of a buffer layer, as current layers of III-V-group semiconductor laser. CONSTITUTION:On an N-InP substrate 11, an N-InP layer of a buffer layer 12, an InGaAsP layer which is an active layer 13, and a P-InP layer which is a clad layer 14 undergo mesa etching, and a current stripe part is formed. Super lattice layers 16 comprising BaxCa1-xF2/InP are formed on the mesa-etched side surface and on the surface of the buffer layer 12 so that the several tens of layers are alternately laminated in the form of bent continuous layers. Therefore, a blocking layer is not necessary at the embedded part. A non-doped InP layer 17 is formed. Since the current constriction layers 16, which are formed by alternately laminating BaxCa1-xF2 and InP, are an insulator, leaking currents are remarkably reduced.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a semiconductor laser light emitting device, in which a current confinement layer of a ■-V group semiconductor laser is formed by mesa-etching a current stripe including an active layer on both sides. By continuously providing a superlattice layer consisting of a barium calcium fluoride layer and an indium phosphorus layer on the surface and the surface of the buffer layer,
This prevents leakage current from the current stripe layer of the semiconductor laser.

[Industrial Application Field] The present invention relates to a semiconductor light emitting device, and particularly to a new current confinement layer structure of a semiconductor laser.

Recently, semiconductor lasers have been widely used as semiconductor light-emitting devices, and there are many types of semiconductor laser structures, but a buried double heterostructure semiconductor laser is used as a relatively common structure. .

Conventionally, this semiconductor laser uses a p-n junction as a current confinement layer, but in a p-n junction semiconductor laser, when the operating temperature of the semiconductor laser reaches a high temperature of about 50 degrees Celsius, the p-n junction The saturation current in the reverse direction increases, and the leakage current at the interface between the current stripe layer and the current confinement layer increases, which limits the high output operation of the semiconductor laser.
Improvements to this are requested.

[Prior Art] FIG. 3 shows a perspective view of essential parts of a semiconductor laser having a conventional structure.

There is an n-1nP substrate 1 with a buffer layer 2 on its surface.
-The active layer 3, which has an InP layer and has a mesa shape, is an I
It is formed of nGaAsP, on which a p-1nP layer is formed as a cladding layer 4, and a p-(nGaAsP layer is formed as a contact layer 5 on its surface).

As a buried structure, a p-I layer is formed on the side surface of the mesa shape including the active layer as a blocking layer to form a current confinement layer.
An nP layer 6 and an n-1nP broaching layer 7 are laminated thereon. Such a laminated structure is formed by epitaxial growth, but Cr/A is grown in the final step.
A semiconductor laser is constituted by an upper electrode 8 made of U and a lower electrode 9 made of A u /S n or the like.

In order to operate the semiconductor laser most efficiently, the active layer 3
It is important to prevent the active layer current flowing through the mesa-shaped current stripe layer including the buffer layer 2 and cladding layer 4 from leaking to the side surfaces of the mesa region.

However, in a current confinement layer having a conventional p-n junction blocking layer, when the temperature during operation of a semiconductor laser increases, the current confinement effect decreases, and the active layer current flows from the current stripe layer in the mesa region to the mesa region. There is an inconvenience that it leaks to the sides of the area.

As described above, the conventional structure has the disadvantage that high output and high temperature operation of the semiconductor laser are severely restricted due to an increase in reverse saturation current in the current confinement layer and leakage current at the interface between the current stripe and the blocking layer. .

[Problems to be solved by the invention] In a buried double heterostructure semiconductor laser, during high-temperature operation of the semiconductor laser, the reverse saturation current increases at the p-n junction of the blocking layer, and the current stripe portion The problem is that leakage current flows at the interface of the blocking layer.

[Means for Solving the Problems] FIG. 1 is a sectional view of essential parts showing the principle of the semiconductor laser of the present invention.

This is a semiconductor laser using InP material as an m-v group, and an n-I layer of a buffer layer 12 is formed on an n-InP substrate 11.
The nP layer, the InGaAsP layer that is the active layer 13, and the p-1nP layer that is the cladding layer 14 are mesa-etched to form a current stripe portion, and on the mesa-etched side surface and the surface of the buffer layer 12. barium fluoride
Calcium/Indium Phosphate (Bax CahxF2/
The superlattice layer 16 consisting of 1 nP) is a bent continuous layer, and several tens of layers are grown alternately. Therefore, there is no need for a blocking layer in the buried part, so non-doped InP is used.
This is the layer 17 produced.

[Function] The current confinement layer of the semiconductor laser of the present invention is different from the conventional 1'n
It is not just a simple p-n junction of P that prevents leakage current,
Utilizing the fact that the superlattice layer Ba x Ca t-x F 2 is a good insulating layer and has an extremely good lattice match with InP, a current confinement layer is formed by stacking these layers alternately. By forming the current confinement layer as a continuous layer from the side surface of the mesa shape to the upper surface of the buffer layer, leakage current can be completely blocked.

[Example] FIG. 2 is an enlarged cross-sectional view of a main part of section E in FIG. 1, in order to explain the current confinement layer of a semiconductor laser according to the present invention.

The n-I layer of the buffer layer 12 is formed on the surface of the n-InP substrate 11.
There is an nP layer, and I is used as the mesa-shaped active layer 13.
An nGaAsp layer is formed, on which a p-InP layer is formed as a cladding layer 14, and a p-InGaAsP layer is formed as a contact layer 15 on the surface thereof.

In the present invention, the mesa-shaped side surface including the active layer as a buried structure and the current confinement layer 16 formed on the buffer layer 12 are continuously laminated on the upper part of the buffer layer and the mesa-shaped side surface. , and the thickness of B a is about 150 people.
It is a superlattice structure in which about 100 layers of x Cax-x F 2 Jlla and 1nP Jifb with a thickness of about 300 people are laminated alternately, and the total thickness is several micrometers of steel.

A non-doped InP layer 17 is formed as a buried layer outside the current confinement layer thus formed.

The BaXCa1-xF2 film can be formed by a molecular beam epitaxial growth method or by an organometallic epitaxial growth method.

In this way, since the current confinement layer formed by alternating layers of BaXCahxF2 and InP is an insulator,
Current leakage from the stripe current layer of the semiconductor laser is significantly reduced to about 1/10 of the conventional current value.

As a result, the threshold current of the semiconductor laser of the present invention is reduced by 20% compared to the conventional one, and the temperature characteristic of the threshold current is about 140 degrees in absolute temperature, which is more than 50 degrees compared to the conventional one. We were able to make improvements.

[Effects of the Invention] As explained above in detail, the current confinement layer of the semiconductor laser according to the present invention has excellent insulating properties, and as a result, it has high quality laser characteristics with low leakage current, and the laser This has a great effect in improving the quality of the equipment.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a semiconductor laser according to the present invention, FIG. 2 is a cross-sectional view of a current confinement layer according to the present invention, and FIG. 3 is a perspective view of a conventional semiconductor laser. In the figure, 11 is n-1nP Substrate, 12 is a buff layer, 13 is an active layer, 14 is a cladding layer, 15 is a contact layer, 16 is a current confinement layer, 17 is a non-doped InP
The layers and are shown respectively.

Claims (1)

[Claims] On both sides of the mesa-etched current stripe including the active layer (13) of the III-V semiconductor laser, and on the boundary between the buried non-doped layer (17) and the buffer layer (12), A semiconductor light emitting device characterized in that a current confinement layer (16) is formed having a superlattice layer consisting of a barium calcium fluoride layer and an indium phosphorus layer alternately laminated.