JPS594870B2 - semiconductor light emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor light emitting device having a double heterojunction stripe structure.

Optical fibers used for optical communications etc. exhibit low transmission loss characteristics in wavelength bands of 0.85 μm, 1.05 μm, 1.3 μm, 1.6 μm, etc.

Therefore, a light emitting device that generates light in the above-mentioned wavelength range is used as a light source. For example, a semiconductor light emitting device having a heavy heterojunction stripe structure using InGaAsP is suitable because it can generate a long wavelength laser beam. In such a conventional double heterojunction stripe structure,
The current injection region is used as the light emitting region, and although attempts have been made to unify the transverse mode, it has been difficult to achieve a stable single mode. The present invention
The purpose is to provide a loss 75 waveguide type semiconductor light emitting device which has a double heterojunction stripe structure of P (5InGaAsP), unifies and stabilizes the transverse mode, and has a loss region on the substrate side. .

Examples will be described in detail below. The figure is an explanatory diagram of an embodiment of the present invention, where 1 is an n-InP substrate, 2 is an n-1
The lossless layer 3 of nGaAsP is n-InP or n-
InGaAsP cladding layer, 4 InGaAsP active layer, 5 p-InP cladding layer, 6, □ electrode, 2
a is a p region formed by Zn diffusion, and 2b is an n region.

The current flows through the n region 2b of width S, and also flows through the cladding layer 3.
The width W25 is thick, but the width 1 portion is thin. Therefore, the width W portion becomes the waveguide region, and the width I portion becomes the loss region. That is, the current injection region has a width S, but the light emitting region has a narrower width w. With such a configuration, spatial hole burning occurs in the injected carrier distribution in the center portion 30 due to stimulated emission, thereby increasing the equivalent refractive index of the center portion, and focusing ( focusing)
effect can be used.

Therefore, it is possible to unify and stabilize the transverse mode, and it is possible to improve the optical output characteristics. When the rat layer 5 is made of InP, it is preferable to form a contact layer of InGaAsP in order to make good ohmic contact with the electrode 6. The above configuration is
n-1nGa with a thickness of 1 μm or more on the n-NP substrate 1
A lossy layer 2 of AsP is formed by liquid phase epitaxial growth, a mask with a width S is applied and Zn is diffused to form a p region 2a as a current blocking region, and a mask with a width 1 is applied to form a p region 2a as a current blocking region. Region 2b is etched to form a groove of width W.

The depth of the p-region 2a is such that it partially enters the boundary between the substrate 1 and the loss layer 2 or the substrate 1, and the groove of the width W is deep enough that the waveguide region of the cladding layer 3 is 1 μm or more. Therefore, there is no problem even if the depth reaches the substrate 1. Next, a cladding layer 3 of n-1nP or n-1nGaAsP is grown by liquid phase epitaxial growth to a thickness of 0.3 in the width 1 range.
The thickness should be about μm.

On this cladding layer 3, a thickness of InG of 0.1 to 0.3 μm is applied.
An active layer 4 of aAsP is formed by liquid phase epitaxial growth, and a p-1nP cladding layer 5 is further formed to a thickness of 1 μm or more by liquid phase epitaxial growth. Then, electrodes 6 and 7 are formed to complete the process, and electrode 7 can be formed on substrate 1 before forming each layer. The composition of each layer is Eg(2), Eg(3), Eg
(3)>Eg(4), the selection is made so as to obtain the relationship Eg(4) x Eg(5).

As explained above, the present invention is based on InP and InGaAs.
In a semiconductor light emitting device having a double heterojunction of P,
A waveguide region and a loss region are formed in the clad layer 3, a loss layer 2 of NGaAsP is formed between the clad layer 3 and the InP substrate 1 to form a loss waveguide, and a waveguide region is formed in the loss layer 2. A current blocking region is formed in a portion other than the width S, which is wider than the width W of the current injection region, that is, a portion having a width l, thereby making it possible to form a light emitting region with a width narrower than the width of the current injection region, It is possible to stabilize the transverse mode and convert it into a single mode.

Note that when the width of the light emitting region is made larger than the width of the current injection region, the threshold current can be reduced, but there is a drawback that the light output characteristics are distorted and a so-called kick is likely to occur. However, as in the present invention, by making the width of the light emitting region narrower than the width of the current injection region, there is an advantage that the transverse mode is stabilized and the linearity of the light output characteristic is improved. Furthermore, since the loss layer 2 serves as a buffer layer, defects in the substrate 1 will not spread, and this also has the advantage of providing stable light emitting characteristics.

[Brief explanation of drawings]

The figure is an explanatory diagram of an embodiment of the present invention. 1 is a substrate, 2 is a loss layer, 3 and 5 are cladding layers, 4 is an active layer, and 6 and 7 are electrodes.

Claims (1)

[Claims] 1. In a semiconductor light emitting device having a double heterojunction of InP and InGaAsP, a waveguide region and a loss region are formed in the cladding layer on the substrate side among the cladding layers above and below the active layer of InGaAsP, and the cladding layer In between and the substrate
A semiconductor light emitting device comprising a GaAsP loss layer, and a portion of the loss layer other than a width wider than the waveguide region is used as a current blocking region.