Semiconductor light emitting device

Details Semiconductor light emitting device Semiconductor light emitting device

2000-09-27

2002-10-15

Jackson, Jerome (Department: 2815)

Active solid-state devices (e.g., transistors, solid-state diode

Incoherent light emitter structure

With particular semiconductor material

C257S098000, C257S097000, C257S190000, C372S045013

Reexamination Certificate

active

06465812

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor light emitting device such as a light emitting diode, a semiconductor laser device, or the like. More particularly, the present invention relates to a semiconductor light emitting device in which a light emitting section made of an AlGaInP type semiconductor material is formed on a GaAs substrate.
2. Description of the Related Art
A semiconductor device using an AlGaInP type semiconductor material has been used as a visible range light emitting device for its advantages such as the capability of achieving the lattice match between a GaAs substrate and the AlGaInP type semiconductor material and that it has the greatest direct transition band gap among the group III-V compound semiconductor materials. Known semiconductor devices using such a material include light emitting diodes, semiconductor laser devices, and the like.
Where an AlGaInP type semiconductor layer is epitaxially grown on a GaAs substrate by using an MOCVD (metal-organic chemical vapor deposition) method, or an MBE (molecular beam epitaxial) method, it is necessary in order to achieve a desirable crystallinity that an impurity such as oxygen is not introduced and that a desirable two-dimensional growth is achieved.
In view of this, Japanese Laid-Open Publication No. 6-57149 discloses method for producing a conventional AlGaInP type semiconductor laser device as shown in
FIG. 9
in which an AlGaInP layer is grown on a plane of an n-GaAS substrate
01
whose principal plane is inclined from the (100) plane toward the [011] orientation.
In this method, first, an n-GaInP or n-AlGaInP buffer layer
82
, an n-AlGaInP cladding layer
83
, a GaInP active layer
84
, a p-AlGaInP cladding layer
85
and a p-GaAs cap layer
86
are grown by an MOCVD method in this order on the n-Gas substrate
81
whose principal plane is inclined from the (100) plane toward the [011] orientation. Then, an SiO
2
film
87
is formed on the p-GaAs cap layer
86
, and the central portion of the SiO
2
film
87
is etched in a stripe pattern. An electrode
811
is formed over the SiO
2
film
87
, and an electrode
810
is formed on the reverse side of the n-GaAs substrate
81
.
In this conventional method for producing a semiconductor laser device, a GaInP or AlGaInP buffer layer is grown on the principal plane of a GaAs substrate which is inclined from the (100) plane toward the [011] orientation, and then an AlGaInP type light emitting section is grown by an MOCVD method.
In this method, however, the effects of inclining the principal plane of the GaAs substrate from the (100) plane toward the [011] orientation do not sufficiently manifest themselves for the following reasons. First, the GaInP or AlGaInP buffer layer is grown directly on the GaAs substrate. Second, a single composition is used for the buffer layer.
SUMMARY OF THE INVENTION
According to one aspect of this invention, there is provided a semiconductor light emitting device at least including: a GaAs substrate whose principal plane is inclined from a (100) plane in a [011] orientation; a first buffer layer of Al
x
Ga
1−x
As (0≦x≦1) provided on the principal plane of the GaAs substrate; a second buffer layer of Al
y
Ga
z
In
1−y−s
P (0≦y≦1 and 0≦z≦1) provided on the first buffer layer; a first cladding layer of Al
s
Ga
t
In
1−a−t
P (0≦s≦1 and 0≦t≦1) provided on the second buffer layer; an active layer provided on the first cladding layer: and a second cladding layer provided on the active layer, wherein an Al content a of the first cladding layer is larger than an Al content y of the second buffer layer.
In one embodiment of the invention, the principal plane of the Gays substrate is inclined from the (100) plane toward the [011] orientation by an angle equal to or greater than about 2°.
In one embodiment of the invention, the Al content y of the second buffer layer is equal to or greater than about 0.3 and less than or equal to about 0.8.
In one embodiment of the invention, a growth temperature for the second buffer layer is different from that for the first cladding layer.
In one embodiment of the invention, a growth temperature for the second buffer layer is equal to that for the first cladding layer.
In one embodiment of the invention, a growth temperature for the first buffer layer is equal to that for the second buffer layer.
In one embodiment of the invention, the second buffer layer is grown while changing a growth temperature therefor in a stepwise or continuous manner.
In one embodiment of the invention, the first cladding layer is grown while changing a growth temperature therefor in a stepwise or continuous manner.
In one embodiment of the invention, the semiconductor light emitting device further includes a current diffusing layer on the second cladding layer.
In one embodiment of the invention, the semiconductor light emitting device further includes a current blocking layer between the second cladding layer and the current diffusing layer.
In one embodiment of the invention, the current blocking layer is provided in a central portion of the semiconductor light emitting device.
In one embodiment of the invention, the current blocking layer is provided in a peripheral portion of the semiconductor light emitting device.
In one embodiment of the invention, the active layer is a quantum well active layer obtained by depositing a number of quantum well layers and a number of barrier layers in an alternating pattern.
In one embodiment of the invention, the semiconductor light emitting device further includes a is current blocking layer provided on the second cladding layer and a cap layer provided on the current blocking layer.
In one embodiment of the invention, the semiconductor light emitting device further includes a light reflecting layer provided closer to the GaAs substrate with respect to the first cladding layer.
According to another aspect of this invention, there is provided a method for producing a semiconductor light emitting device through a vapor phase deposition method on a principal plane of a GaAs substrate which is inclined from a (100) plane toward a [011] orientation, the method including the steps of: (a) growing a first buffer layer of Al
x
Ga
1−x
As (0≦x≦1) on the principal plane of the GaAs substrate; (b) growing a second buffer layer of Al
y
Ga
x
In
1−y−z
P (0≦y≦1 and 0≦z≦1) on the first buffer layer; and (c) sequentially growing a first cladding layer of Al
z
Ga
t
In
1−s−t
P (0≦s≦1 and 0≦t≦1) on the second buffer layer, an active layer on the first cladding layer, and a second cladding layer on the active layer, wherein an Al content a of the first cladding layer is larger than an Al content y of the second buffer layer.
In one embodiment of the invention, the step (a) is performed at a growth temperature between about 600° C. and about 700° C.; the step (b) is performed while increasing a growth temperature from a temperature between about 600° C. and about 700° C. to a temperature between about 700° C. and about 850° C.; and the step (c) is performed at a growth temperature between about 700° C. to about 850° C.
In one embodiment of the invention, the vapor phase deposition method is an MOCVD method.
In one embodiment of the invention, the vapor phase deposition method is an MBE method.
In one embodiment of the invention, the principal plane of the GaAs substrate is inclined from the (100) plane toward the [011] orientation by an angle equal to or greater than about 2°.
In one embodiment of the invention, the Al content y of the second buffer layer is equal to or greater than about 0.3 and less than or equal to about 0.8.
In one embodiment of the invention, a growth temperature for the step (b) is different from that for the step (c).
In one embodiment of the invention, a growth temperature for the step (b) is equal to that for the first cladd

Affiliated with

Also associated with

Rating

Semiconductor light emitting device does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Semiconductor light emitting device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor light emitting device will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2997446