JPS63216396A - Semiconductor light emitting devices - Google Patents

Abstract

PURPOSE:To facilitate obtaining a highly reliable laser by removing the effect of the damage of a reflecting surface by providing a non-exciting region, etc. inside the reflecting surface in light emitting devices formed by facing the reflecting surfaces each other by etching. CONSTITUTION:Inside the edge faces 6, 7 of a resonator formed by facing each other by etching in semiconductor light emitting devices, a window region which is made transparent against non-exciting regions 9, 9' or the wavelength of the oscillation of a laser is provided. For example, after an n-type InP clad layer 2, an InGaAsP active layer 3, a p-type InP clad layer 4 and a p-type GaInAsP cap layer 4' are formed on an n-type InP substrate 1, reflecting surfaces 6, 7 are formed by dry etching by using a TiO2 film as a mask material 5. Then, after the exposed active layer 3 is slightly removed by shaving by selective etching, In and P are carried in the groove of the active layer from the clad layers 2, 4 of the both sides of the active layer 3 by heating to 600 deg.C in the atmosphere of PH3 and the non-exciting regions 9, 9' are provided by forming InP single crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a semiconductor light emitting device manufactured by cutting out a resonator end face by etching, and particularly provides a semiconductor light emitting device with improved reliability.

(Conventional technology) In recent years, there has been remarkable development in the fields of optical communication and optical information.
Their practical application is progressing rapidly. Under these circumstances, semiconductor light emitting devices with excellent directivity and monochromaticity have become indispensable as light sources for lasers, which are signal media.

When manufacturing the above-mentioned semiconductor light emitting device (hereinafter simply referred to as a light emitting device), the laser resonator end face of the device, that is, the surface that reflects the laser generated within the light emitting device and is perpendicular to the output direction of the laser, is During formation, the interfold surfaces of the crystal are usually used as they are as resonator end surfaces (hereinafter referred to as reflective surfaces). Moreover, it is widely used because it can be obtained by a simple operation of interfolding.

There is no problem with a light emitting element that utilizes the interfold surface as a reflective surface as long as the element is used alone.

However, since the crystal is discontinued at the interfold plane, optical functional devices such as a detector and a driving circuit cannot be integrated into such a light emitting element. Therefore, in order to construct an optical integrated circuit or optical integrated device based on a light emitting element, it is necessary to create a laser reflecting surface by a method other than between the folds.

In order to cope with this problem, a method has conventionally been used in which a surface that is not an interfold surface is cut flat by etching to form a reflective surface. General etching methods include chemical etching, which uses chemical reactions, and dry etching, which uses low-temperature plasma of molecules, atoms, or ions in an excited state. This varies depending on the type of surface, and as it is, it is unsuitable for use as a reflective surface. On the other hand, dry etching has low etching selectivity, excellent yield and reproducibility, and good microfabrication, so it is the most suitable method for forming reflective surfaces for integration.

Light-emitting devices include InP-based and (3aAs-based), and their structure generally has a double heterostructure in which there are two heterojunctions in which semiconductor crystals of different types with the same lattice constant are joined in the same crystal orientation. For example, in InP system, I
An InP single crystal cladding layer is grown on an nP single crystal substrate, and an InGaAsP single crystal active layer and an InP single crystal cladding layer are grown on top of the InP single crystal cladding layer.
It has a multilayer structure in which single-crystal cladding layers are grown in sequence. The thus laminated crystals are cut out by a method such as interfolding, and electrodes are formed to form a light emitting element. By applying a voltage to the element, a laser is emitted in a direction perpendicular to the stacking direction of each single crystal.

(Problem to be solved by the invention) A laser reflective surface is formed by dry etching,
When a light emitting device is fabricated, the reflective surface may be subjected to excessive physical damage due to low temperature plasma during dry etching or chemical alteration due to adsorption of oxygen, moisture or other impurities in the operating atmosphere. On the other hand, the active layer that makes up the light emitting device is the part that performs laser oscillation, but if the active layer exposed to the reflective surface is damaged as described above, the instability of the laser oscillation state will increase and the lifespan will be shortened. There was a problem of decreased reliability due to shorter lengths.

[Means for solving problems]

In view of this, as a result of various studies, the present invention has developed a highly reliable semiconductor light emitting device.In a light emitting device in which reflective surfaces are formed facing each other by etching, a non-excited region is provided inside the reflective surfaces. This is a characteristic feature.

(Function) In order to form the above-mentioned non-excited region, when or after cutting out the laser reflecting surface by etching, only the active layer is selectively etched slightly deeper to create a concave shape. After that, the atoms constituting the crystal are transported from the cladding layer protruding on both sides of the groove to the concave groove using the mass transport method, forming the same crystal as the cladding layer, and smoothing out the surface irregularities. It can be removed and used as a new reflective surface.

(Example) As an example of the present invention, I
An rlGaAs P/IrlP semiconductor light emitting device is shown in FIGS. 1(a), (b), and (c). First, Figure 1 (a)
As shown in the figure, an n-type InP single crystal cladding layer (2) is grown on an n-type InP single crystal substrate (1) in the same crystal orientation as the substrate (1), and on top of the cladding layer (2). InGa
The ASP single crystal active layer (3) is crystal-grown to form a heterojunction, and the p-type -I layer is roughly grown on the active layer (3).
nP single crystal cladding layer (4), p-type-GaInAs
After crystal-growing a P cap layer (4°) to form a heterojunction, T
The i0z film was applied as an etching mask material (5), and then the surface on which the mask material (5) was formed was etched out according to the etching pattern of the mask material (5). Reflective surfaces (6) and (7) were formed on opposing surfaces other than the inter-fold surfaces in a direction perpendicular to the direction of each layer by dry etching using low-temperature plasma using 12-Ar gas.

Next, as shown in Figure 1 (b), the reflective surface (6), (
After slightly scraping off the active layer (3) exposed in 7) by selective etching, this semiconductor crystal (8) is
Heating to 600'C in H3 atmosphere, mass transport phenomenon creates Clarado layers (2), (4) on both sides of active layer (3).
1n and P@ are transported to the groove of the selectively etched active layer, and as shown in FIG. Planarize surfaces (6) and (7). Then mask material (5)
) is removed, and electrodes (10
), (11) were formed.

It was confirmed that a non-excited region that does not contribute to laser oscillation was formed in the active layer of the laser reflecting surface of the semiconductor light emitting device fabricated in this way.

〔Effect of the invention〕

As described above, the present invention has industrially significant effects such as being able to eliminate the effects of damage to the laser reflecting surface in the semiconductor light emitting device and producing a highly reliable laser.

[Brief explanation of the drawing]

Figures 1 (a), (b), and (c) show one embodiment of the present invention, in which (a) is a side sectional view of a single crystal grown in layers, and (b) is a selected active layer. (C) is a side sectional view showing the etched state, and (c) is a side sectional view showing the final product. 1...N-type InP substrate 2...N-type InP cladding layer 3...
...I nGaASP active layer 4...P-type 1nP cladding layer 4°...P-type GaInA
SP cap layer 5...Mask material 6.7...Reflecting surface 8...Semiconductor light emitting element 9.9°...Non-excitation region to, ii...electrode

Claims (1)

[Claims] 1. A semiconductor light emitting device in which resonator end faces are formed by etching to face each other, and the semiconductor light emitting device is characterized in that a non-excitation region or a window region transparent to the oscillation wavelength of a laser is provided inside the resonator end face.