JPS62139381A - Semiconductor light emitting element - Google Patents

Abstract

PURPOSE:To make a light emitting spot small by reducing the leakage current from a cutout and restraining natural light emitting components by separating a cladding layer into a cladding layer on the active layer side and a current constriction layer. CONSTITUTION:On an N-type GaAs substrate 11, an N-type buffer layer 12, an N-type first cladding layer 13, a P-type active layer 14, and a second cladding layer 15 are laminated. This cladding layer 15 is composed of a current constriction layer 16 composed of an N-type third cladding layer 16a on the side of the active layer 14 and a GaAs layer 16b. On a wafer thus formed, a masking member having a stripe vertical to a cleavage direction is formed and the constriction layer 16 is selectively etched by use of an etching solution so as to form a cutout 17. Furthermore, a P-type light guiding layer 18 and an ohmic layer 20 are grown in order to fill the cutout 17. Then, the leakage current from the cutout 17 is reduced to make a light emitting spot small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a semiconductor light emitting device, and particularly to a Raded diode using GaAIAa and having an emission wavelength of around 800 nm.

[Technical background of the invention]

Conventionally, MOCVD method or MBE (Molec
ularf3eam Bpj taX)') method M'v
For example, the one shown in FIG. 2 is known as stavrZi,t-)'.

1 in the figure is an N-type Q a AS substrate. On this substrate 1, an N-type GaAs layer (buffer layer) 2 and an N-type GaAs layer (first cladding layer) are formed.
3 and a Ga1-yAlyAs layer (active layer) 4 are sequentially provided. On the active layer 4, P-type Ga1-zA
lzAs layer (second cladding layer) 5 and N-type GaAs
A layer 6 is provided.

This current intercalation layer 6 is provided with a striped defect 7 that reaches a predetermined depth of the second cladding layer 5 . This defective part 7 contains P-type Ga1-vAevAs#
(Light guide layer) 8 and P type Qai-uAguAsi
(Third cladding layer) 9 is embedded. Note that this filling creates an effective refractive index difference between the inside and outside of the defective portion 7, and controls the mode in the direction horizontal to the active layer.

A P-type GaAs layer (ohmic layer) 10 is provided on the third cladding layer 9.

[Problems with background technology]

Incidentally, the above-mentioned Radede diode is excellent as a refractive index guided type Radede having a flat active layer.

However, sufficient mode control requires detailed structural control.

For example, x=o, 45 t y=0.12 s z=0
．． 45° When v=0.25 and u=0.45, the thickness of each layer is 1.5 μm for the first cladding layer 3, 0.08 μm for the active layer 4, and 10 μm% for the second cladding layer 5. Current constriction layer interposed LO μrtc, light guide layer 8 is 0.25 pm
.

It is necessary to control the cladding layer 9 of 83 to be 1.2 .mu.m, the distance dt-0 between the active layer 4 and the light guide layer 8 to be 3 .mu.m, and the width l of the bottom surface of the defective portion 7 to be approximately 2 .mu.m. However, even in this case, the current flows not only directly under the defective portion 7 but also through the second cladding layer 5 on the side surface, so that the current is injected into the relatively wide slope of the active layer 4. Therefore, there is a disadvantage that the luminescent chain acid becomes wide and the number of spontaneous luminescent components increases.

Purpose of the Invention The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor light emitting device that can suppress spontaneous luminescence components.

[Summary of the invention]

The present invention replaces the conventional second cladding layer with a second cladding layer near the active layer.
By creating a structure in which the current sandwiching layer is separated into a cladding layer and a current sandwiching layer consisting of at least a third cladding layer having a current sandwiching function), current leakage from the side surface of the defective part of the current sandwiching layer restripe can be prevented. The main idea is to reduce the amount of light emitted from natural light and suppress the natural luminescent component.

[Embodiments of the invention]

Hereinafter, a radar diode according to an embodiment of the present invention will be explained in the order of manufacturing steps with reference to FIGS. 1(a) to 1(c).

First, on an N-type QaAa substrate 11, an N-type GaAs f* (buffer layer) 12 with a thickness of 1μ and an N-type Qax-xAgxA4 with a thickness of 1.5μ (first clad W1
)13, P-type Qa 1-yAeY with a shoulder thickness of 0.08μ
A” layer (active layer 14, thickness 0.3μ P type Qa
l-zAgzAs layer (second cladding layer) 15° thickness 1
．． A 2 μm N-type Qi l-wAJwAs layer (third glue 2 rad layer) 16a and a thickness of 1. Opm OGaAs
A current intercalating layer 16 consisting of a layer (If-V group compound semiconductor layer) 16b was successively grown (as shown in FIG. 1(, )).

Subsequently, a mask material (not shown) having stripes with a width of 3 μm perpendicular to the cleavage direction of the wafer was formed on the substrate 11 by photolithography. Here, the mask material may be a thin film that is resistant to the etching solution. Next, the current intercalating layer 1 is etched using a sulfuric acid-based etching solution.
6 was selectively etched to form a defect 17 having a width of about 2.5 μm at the bottom (as shown in FIG. 1(b)).

Furthermore, a P-type Qal-vAJvAs layer (light guide layer) 18 with a thickness of 0.25 μm and a thickness of 1.0 μm were formed by MOCVD.
5. A umOP-type Ga 1-uAJuAs layer (fourth cladding layer) 19 and a P-type GaAs layer (ohmic layer) 20 with a thickness of 4 μm were grown in sequence so as to fill the defect 17 (Fig. 1). (C) As shown). However, x = z
= w = u = 0.45, y = 0.12,
V = 0.35.

According to the present invention, the conventional second cladding layer is replaced with the active layer 14.
the second cladding layer 15 close to Gai-vtkl1w
Current interpolation f consisting of As layer 16m and QaAs layer 16b
Since the structure is separated into 91g and 91g, the defective part 17
It is possible to reduce current leakage from the side surface of the device compared to the conventional method, and to obtain a good radar with suppressed natural luminescence components. In fact, the current injection portion of the active low region is limited to approximately 3 μm or less, making it possible to obtain a small light emitting spot.

In addition, although the above-mentioned example described the case where there are two layers of intercalated currents, the present invention is not limited to this.

For example, the GaiS layer 16b may be omitted, and at least one layer of the third cladding layer 16a may be used as long as it has both the current interpolation function and the cladding layer function. however,
It is better to form a Ga AS layer on the upper layer as in the example.
It is preferable that the subsequent crystal 7 growth grows directly on the 2 rad layer.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide a semiconductor light emitting device that can suppress natural luminescent components.

[Brief explanation of drawings]

FIGS. 1A to 1C are cross-sectional views showing a Raded diode according to an embodiment of the present invention in the order of manufacturing steps, and FIG. 2 is a cross-sectional view of a conventional Raded diode. 1 No. GaAs substrate, 12 Buffer layer 13
゜15.16a, 19... cladding layer, 14... active layer, 16... current intercalating layer, 16b... GaAS layer, 17... defective part, 18... light guide layer, 20...
・Ohmic layer. Applicant's agent Patent attorney Takehiko Suzue Figure 2

Claims (1)

[Claims] A first cladding layer of a first conductivity type, an active layer provided on this cladding layer and serving as a light emitting region, a second cladding layer of a second conductivity type provided on this active layer, and a second cladding layer of a second conductivity type provided on this active layer. a second conductivity type current constriction layer provided on the second cladding layer and having a stripe-shaped defect and at least a third cladding layer; 1. A semiconductor light emitting device comprising: a light guide layer having a large refractive index; and a fourth cladding layer provided in the defect portion and having a smaller refractive index than the light guide layer.