Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure – With particular semiconductor material
Reexamination Certificate
1999-07-13
2001-02-20
Meier, Stephen D. (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
With particular semiconductor material
C257S095000, C257S097000
Reexamination Certificate
active
06191439
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a structure of semiconductor including nitride which emits lights due to a transition of band-to-band of an active layer.
2. Related Background Art
Because an optical transition of semiconductors including a gallium nitride, i.e. InAlGaN, is a direct transition, it is possible to allow lights to efficiently emit and recombine. Furthermore, because a transition energy of the semiconductors including a gallium nitride is widely ranged from 2 to 6.2 eV, the semiconductors are developed as efficient light emitting device materials such as a semiconductor laser or a high-luminance visible LED (Light Emitting diode). Furthermore, semiconductors including gallium nitride has a feature that it is possible to emit lights at an ultraviolet wave length as III-V compound diodes. Accordingly, it may possible to replace conventional ultraviolet luminants with the semiconductors including gallium nitride.
A band-gap energy of InxGa1-xN, which is one type of the semiconductors including gallium nitride, is variable by changing an indium (In) composition x. Because of this, it is possible to use the InxGa1-xN as an active layer for avisible light emitting device.
At this time, a LED, of which a light emitting layer is a mix crystal made of InGaN, is realized, and a semiconductor laser which oscillates by a current injection is realized.
However, an optical mechanism of the LED, of which the active layer is formed of a crystal that a constituent ratio x is high, where x is equal to or less than 0.05, is different from the optical mechanism of a crystal that the constituent ratio x is low. In order to realize efficient ultraviolet LED, it is desirable to improve electric properties by improving a method for allowing the crystals to grow and an device structure.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a semiconductor light emitting device that it is possible to efficiently emit lights and to allow lights in an ultraviolet wave length region to efficiently emit.
In order to achieve the foregoing object, a semiconductor light emitting device, comprising:
an active layer in a thickness equal to or more than 50 nm; and
a semiconductor including nitride which has a stacked structure and is arranged at both sides of said active layer,
wherein a current injection area of said semiconductor including nitride is equal to or less than 5×10
−4
cm
2
, and
lights are emitted due to a transition of band-to-band of said active layer.
According to the present invention, in a semiconductor light emitting device for allowing lights to emit by injecting a current into a semiconductor including nitride which sandwiches an active layer and has a stacked structure, a thickness of the active layer is set equal to or more than 50 nm, and a current injection area is set equal to or less than 5×10
−4
cm
2
. Because of this, it is possible to obtain a semiconductor light emitting device capable of efficiently emitting lights at an ultraviolet wave length.
Furthermore, a semiconductor light emitting device, comprising:
a buffer layer formed on a sapphire substrate;
an n-GaN contact layer formed on said buffer layer;
an n-AlGaN clad layer formed on said n-GaN contact layer;
an active layer formed on said n-AlGaN clad layer;
a p-AlGaN clad layer formed on said active layer;
a p-GaN contact layer formed on said p-AlGaN clad layer;
a current block layer formed on a portion of said p-GaN contact layer;
an n-side electrode formed on said n-GaN contact layer, said n-side electrode being separated from said n-AlGaN clad layer; and
a p-side electrode formed on said p-GaN contact layer and said current block layer,
wherein a thickness of said active layer is equal to or more than 50 nm, and
said p-side electrode has an area equal to or less than 5×10
−4
cm
2
, except for a region overlapping with said n-GaN current block layer.
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patent: 5751752 (1998-05-01), Shakuda
patent: 5981978 (1999-11-01), Mushiage et al.
patent: 0803 916 A2 (1997-04-01), None
patent: 99113649 (2000-06-01), None
patent: 09312442 (1997-02-01), None
Masahiko Inamori, et al., “Direct Patterning of the Current Confinement Structure for p-Type Column-III Nitrides by Low-Energy Electron Beam Irradiation Treatment,” Jpn. J. Appl. Phys., vol. 34, Pt. 1, No. 2B, pp. 1190-1193, 1995.
Hogan & Hartson LLP
Kabushiki Kaisha Toshiba
Meier Stephen D.
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