JPS593873B2 - 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, and 1.6 μm.

Therefore, a light emitting device that generates light in the above-mentioned wavelength range is used as a light source. For example, GaAlAs, In
Semiconductor light emitting devices having a double heterojunction stripe structure using GaAs, GaAsSb, InGaAsP, etc. have been proposed. In such conventional semiconductor light emitting devices, 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 in practice. Furthermore, the linearity of the relationship between drive current and optical output was not sufficient. The present invention aims to unify and stabilize transverse modes, and to improve optical output characteristics.

Examples will be described in detail below. FIG. 1 is an explanatory diagram of an embodiment of the present invention, where 1 is an n-GaAs substrate, 2 is an n-GaAs substrate, and 2 is an n-GaAs substrate.
(aAlAs cladding layer, 3 is GaAs or GaAl
As active layer, 4 is GaAlAs layer, 4a is p-GaAl
4b is an n-20 GaAlAs cladding layer, 5 is a p-GaAs layer, 6 is a p+ ohmic contact layer, and T38 is an electrode. Cladding layer 2 is 1μml
The active layer 3 has a thickness of 0.1 to 0.3 μm, the cladding portion 4a has a width w of 1 μm or more, and the cladding portion 4b has a thickness of about 0.3 μm25. The cladding portion 4a has a width s including a portion having the same thickness as the cladding portion 4b. The cladding portion 4b is formed by making the cladding layer 4 n-type by s-diffusion or the like, or increasing the resistance 30 by implanting protons.

The ohmic contact layer 6 is formed by Zn diffusion or the like to make good ohmic contact with the electrode 7. In this case, since the Zn diffusion region is far from the active layer 3, defocusing occurs due to a 35% decrease in the equivalent refractive index of the active layer 3 caused by Zn diffusion.
ng) effect can be avoided. Since the current between the electrodes T and 8 flows through the cladding part 4a, the width of the current injection region is s, and a part of the cladding part 4a and the cladding part 4
Since the thickness of b is small and the metal electrode 7 is provided on the top thereof, the light loss in the portion other than the width w is large, and the width of the light emitting region is w.

Since the width w of the light emitting region is narrower than the width s of the current injection region, spatial hole burning (HOlebu) occurs in the injection carrier distribution at the center due to stimulated emission.
ming), which increases the equivalent refractive index at the center and causes focusing due to carrier distribution (FO
cusing) effect can be used. Therefore, the transverse mode can be unified and stabilized, and the optical output characteristics can be improved. As a specific example, n
- n-GaO. 7AlO. A 3As cladding layer 2 with a thickness of 2 μm 1 is formed thereon with P{AO. 92A
lO. The active layer 3 of O8As has a thickness of 0.1 μm, and p-GaO. 7AlO. 3As cladding layer 4 with a thickness of 1
．． A layer of p-GaA 8 of 1 μm thick was formed thereon by liquid phase epitaxial growth, and etched using a mask with a width of W. The thickness of the cladding layer 4 other than the mask was set to 0.3 μm, and a mask with a width of S was applied. Then, sulfur diffusion was performed to make the dotted and diagonal cladding portion 4b n-type, and then Zn was diffused to form the ohmic contact layer 7.

Then, as the electrode 7, an electrode having a multilayer structure of Ti-Pt-Au was formed on the entire surface. Note that the electrode 8 can have the same structure as the electrode 7, and can also be formed before liquid phase epitaxial growth. In such a configuration, s
When w=10 μM and w=7 μm, the current-light output characteristics were as shown in FIG.

The threshold current is 100 mA, the emission wavelength is in the 0.85 μm band, and the linearity is good until the optical output is 15 mW.
Moreover, the transverse mode was stable with a single fundamental mode. Although the foregoing example is for a double zero junction structure of GaAlAs and GaAs, other multicomponent compounds can also be used.

For example, the substrate 1 is InP, the cladding layer 2 is InP, the active layer 3 is InGaAsPl, the cladding layer 4 is InP, and the layer 5 is InP.
It can be nP or InGaAsP, with layer 5 being In
When it is made of P, the portion corresponding to the ohmic contact layer 7 is made of InGaAsP. When constructed from such InGaAsP and InP, the luminescent growth can be approximately 0.9 to 1.4 μm. As explained above, in the present invention, the second cladding layer 4 is
A convex cross section is formed by a thick part with a width corresponding to the width w of the light emitting region and parts thinner than the first cladding layer 2 on both sides thereof, and a part of the thin part is opposite to the active layer 3. As a conductivity type or high resistance region, the width W of the light emitting region is narrower than the width S of the current injection region, which can stabilize the transverse mode and improve the linearity of the light output characteristics. There is an advantage that it can be done.

It also has the advantage of being relatively easy to manufacture.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the present invention, and FIG. 2 is a current-light output characteristic curve diagram of a semiconductor light emitting device according to an embodiment of the present invention. 1 is a substrate, 2 and 4 are cladding layers, 3 is an active layer, 6 is an ohmic contact layer, and 7 and 8 are electrodes.

Claims (1)

[Claims] 1. A semiconductor light emitting device with a double heterojunction stripe structure has a first cladding layer, an active layer, and a second cladding layer on a substrate, and the second cladding layer has a width of a light emitting region. The cross-section is convex with a thick portion having a corresponding width and thinner portions than the first cladding layer on both sides of the thick portion, and the width of the current injection region is wider than the width of the light emitting region. A semiconductor light emitting device characterized in that the thin portions on both sides of the width corresponding to the width of the injection region are regions of the opposite conductivity type or high resistance to the active layer, and a metal electrode is provided on the entire upper surface.