JPS61141193A - Semiconductor light-emitting device - Google Patents

Abstract

PURPOSE:To contrive the flattening of the buried growth layer and the improvement of the quantum efficiency of a semiconductor light-emitting device by a method wherein a stripped active region and a semiconductor region; wherein the active region is buried and a semiconductor layer, which forms a P-N junction with the InGaAsP layer to be provided on the InP substrate, is included; are provided on the InGaAsP layer. CONSTITUTION:An N-type InGaAsP layer 2 is provided on an N-type InP substrate 1, and moreover, an N-type InP confinement layer 3, an InGaAsP active layer 4, a P-type InP confinement layer 5 and a P<+> type InGaAsP contact layer 6 are provided and a mesa etching is performed in a stripe form. Then, the inverse N-P junction of a P-type InP layer 8 and an N-type InP layer 9 is formed on a P-type InGaAsP layer 7 being abutted on the vicinity of the heterojunction interface of the confinement layer 5 and the active layer 4. By this way, as am embedding growth progresses on the surface of the InGaAsP layer 7, which is parallel to the surface of the substrate 1, in the mesa etching to enable the striped region of the InP/InGaAsP system BH laser to form, the control to the flattening of the buried growth layer becomes easier. As a result, the leakage current in the operating state of the device reduces and the quantum efficiency thereof is made to improve.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to semiconductor light emitting devices, particularly InP/InGaAs
The present invention relates to a semiconductor light emitting device in which a buried semiconductor region of a P-based Bl (laser) grows parallel to a substrate surface to improve characteristics such as quantum efficiency.

2. Description of the Related Art In systems such as optical communications that use light as a medium for information signals, semiconductor light emitting devices play an extremely important role as light sources that generate optical signals.

Therefore, in order to increase the sophistication and diversification of optical communication systems, there is a demand for further improvements in the characteristics of semiconductor light emitting devices, especially lasers, such as their oscillation modes and quantum efficiency.

[Conventional technology]

Wavelength 1.1 suitable for transmission using silica fiber for optical communication
As a semiconductor laser with a band of ~1.7n, InP
/ BH (Buried Heteros) using InGaAsP compound semiconductor whose schematic side sectional view is shown in
structure) lasers are known.

To manufacture this BH laser, first, for example, an n-type 1nP confinement layer 2 is placed on the (100) plane of an n-type InP substrate 21.
2. A heterojunction stacked structure consisting of an InGaAsP active layer 23, a p-type InP confinement layer 24, and a p+ pear-shaped 1nGaAsP contact layer 25 is grown by, for example, a liquid phase epitaxial growth method (hereinafter abbreviated as LPE method).

For example, silicon dioxide (SiO□
) is provided in the <011> direction,
Mesa etching was performed using a methanol solution of bromine (Br), and p-type InP [26
Then, an n-type rnP layer 27 is buried and grown. Note that a p-side electrode 28 is provided on the p+ type InGaAsP contact layer 25, and an n-side electrode 29 is provided on the back surface of the substrate 21.

However, in the mesa etching step of the manufacturing method, as schematically shown in FIG.
p+ type [nGaAsP contact layer 25 and upper 2
Side etching progresses significantly in the p-type 1nP confinement layer 24 adjacent to the etching layer 24, causing a constriction in the confinement layer 24, and the bottom surface of the etching region is greatly inclined.

For this reason, it is not easy to control the width of the InGaAsP active layer 23 to the optimum width for the fundamental zero-order transverse mode, and during the epitaxial growth of the buried growth layer, it is difficult to control the width of the InGaAsP active layer 23 to the optimum width for the fundamental zero-order transverse mode. The layer 26 and the n-type InP layer 27 are easily grown as shown in the figure, and the np junction interface between the two layers is formed by forming the p-type InP confinement layer 2 as shown in figure 2.
It becomes extremely difficult to control the contact near the heterojunction interface with the active layer 23 of No. 4.

[Problem to be Solved by the Invention 1] As explained above, in the conventional structure of the InP/InGaAsP BH laser, there is a problem in the mesa etching shape of the stripe region, and it is extremely difficult to realize the expected laser characteristics.

[Means for solving problems]

The above problem is solved by providing a first semiconductor layer made of an indium gallium arsenide phosphorus compound on an indium phosphorus compound semiconductor substrate, and forming an active region on the first semiconductor layer in which a striped double heterojunction is felt. The semiconductor light emitting device according to the present invention is provided with a semiconductor region including a second semiconductor layer that embeds the active region and is made of an indium gallium arsenide phosphorus compound and forms a pn junction with the first semiconductor layer. be done.

[For production]

In the semiconductor light emitting device according to the present invention, InP is formed on an InP substrate.
A GaAsP layer is provided, and a double heterojunction structure including an active region made of, for example, InP/InGaAsP layer is epitaxially grown on this InGaAsP layer. In mesa etching to make this double heterojunction structure into a stripe shape, the above-mentioned InGaAs
Since the P layer acts as an etching stop layer and forms the bottom surface of the etching region, the buried growth layer becomes flat and can be precisely controlled.

A pn junction between the buried growth layer and the InGaAsP layer is formed by a second InGaAsP layer to reduce leakage current and improve quantum efficiency in the operating state.

〔Example〕

The present invention will be specifically explained below with reference to an embodiment whose schematic side sectional view is shown in FIG.

In the figure, l is an n-type InP substrate and its (100
) surface according to the invention, e.g. the luminescence wavelength λg=
A 1.1 μm n-type 1nGaAsP layer 2 is provided.

3 is an n-type 1nP confinement layer with a thickness of about 0.3 μm, and 4 is a 1nGaA layer with λg=1.3 μm and a thickness of about 0.11 Im.
sP active layer, 5 is a p-type 1nP confinement layer with a thickness of about 0.6 μm, and 6 is a p-type confinement layer with λg = 1.3 and a thickness of about 0.2 μm.
This is a + type TnGaAsP contact layer, and the above semiconductor layers 3 to 6 are mesa-etched in a stripe shape.

- In the semiconductor layer stack structure that embeds this stripe region, 7 is a p-type InGaAsP layer with λg = 1.1 μm;
8 is a p-type 1nP layer, 9 is an n-type InP layer, and this layer 9 and layer 8
An np reverse junction is formed to block leakage current, and this junction is connected to the InGaAsP of the p-type 1nP confinement layer
It is in contact with the vicinity of the heterojunction interface with the active layer 4.

Further, 10 is a p-side electrode in ohmic contact with the p+ pear-shaped 1nGaAsP contact layer 6, and 11 is an n-side electrode in ohmic contact with the back surface of the n-type 1nP substrate 1.

The mesa etching of the semiconductor layers 3 to 6 in this example is as follows:
For example, by forming a mask in a stripe shape with SiO□,
The nP layer is etched with a hydrochloric acid (HCI)-based etchant, and the InGaAsP IiJ is etched with a sulfuric acid (HzSOa)-based etchant, whereby the (100) plane of the n-type 1nGaAsP layer 2 appears, and the p-type 1nGaAsP layer 7 to the n-type rnP layer 9 are etched. Buried growth is easily performed on this (100) plane by a liquid phase epitaxial growth method, etc., and a flat and parallel buried layer is formed.

〔Effect of the invention〕

As explained above, according to the present invention, InP/InGa^
In the mesa etching that forms the stripe region of the sP-based BH laser, (100) parallel to the semi-dedicated substrate surface is exposed, and buried growth mainly proceeds on this (100) plane, making it difficult to control the buried layer. This is easy to do, and pn junctions on the substrate side of this buried layer are formed between the InGaAsP layers, which particularly reduces leakage currents and improves the quantum efficiency in the operating state.

[Brief explanation of the drawing]

FIG. 1 is a schematic side sectional view showing an embodiment of the present invention, FIG. 2 is a side sectional view aimed at a Bll laser, and FIG. 3 is a schematic side sectional view showing a conventional example. In the figure, 1 is an n-type InP substrate, 2 is an n-type 1nGaAsP layer, 3 is an n-type 1nP confinement layer, 4 is an InGaAsP active layer, 5 is a p-type 1nP confinement layer, 6 is a p+ pear-shaped 1nGaAsP contact layer, and 7 is a pear-shaped 1nGaAsP contact layer. p-type In
8 is a p-type InP layer, 9 is an n-type InP layer, 10 is a p-side electrode, and 11 is an n-side electrode. jPl Akile 13EJ

Claims (1)

[Claims] a first semiconductor layer made of an indium gallium arsenide phosphorous compound on an indium phosphorus compound semiconductor substrate;
an active region that forms a striped double heterojunction on the semiconductor layer; a second semiconductor layer that buries the active region and is made of an indium gallium arsenide phosphorous compound and forms a pn junction with the first semiconductor layer; What is claimed is: 1. A semiconductor light emitting device comprising: a semiconductor region including a semiconductor region;