Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure – With heterojunction
Reexamination Certificate
2001-09-11
2002-09-17
Chaudhuri, Olik (Department: 2813)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
With heterojunction
C257S097000
Reexamination Certificate
active
06452216
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a nitride semiconductor light emitting device having an improved emission life and an apparatus including the same.
2. Description of the Prior Art
Japanese Patent Laying-Open No. 2000-124500 discloses a technique of forming convex portions on a GaN layer stacked on a sapphire substrate, flatly covering the convex portions with a GaN underlayer and forming a gallium nitride semiconductor laser device on the GaN covering layer for improving the emission characteristics of a nitride semiconductor light emitting device. According this gazette, the distance between adjacent ones of the convex portions is preferably within the range of 1 to 10 &mgr;m, the width of the upper surfaces of the convex portions is preferably at least 1 &mgr;m, and the height of the convex portions is preferably within the range of 0.1 to 2 &mgr;m. This gazette also describes that the sapphire substrate may be replaced with a GaN substrate.
Even if the sapphire substrate is replaced with a GaN substrate in the nitride semiconductor laser device according to the prior art, however, the oscillation life is still insufficient.
SUMMARY OF THE INVENTION
Accordingly, a principal object of the present invention is to provide a nitride semiconductor light emitting device having a long oscillation life.
According to the present invention, the nitride semiconductor light emitting device includes a worked substrate including grooves and lands formed on a main surface of a nitride semiconductor substrate, a nitride semiconductor underlayer covering the grooves and the lands of the worked substrate and a nitride semiconductor multilayer emission structure including an emission layer including a quantum well layer or both a quantum well layer and a barrier layer in contact with the quantum well layer between an n-type layer and a p-type layer over the nitride semiconductor underlayer, while width of the grooves is within the range of 11 to 30 &mgr;m and width of the lands is within the range of 1 to 20 &mgr;m.
The width of the grooves is preferably larger than the width of the lands, and the depth of the grooves is preferably within the range of 1 to 10 &mgr;m.
The longitudinal direction of the grooves or the longitudinal direction of the lands is preferably substantially parallel to the <1-100> direction or the <11-20> direction of a crystal of the substrate.
The nitride semiconductor underlayer preferably contains Al. Further, the nitride semiconductor underlayer preferably contains In
x
Ga
1−x
N (0.01≦x≦0.18).
The quantum well layer preferably contains at least any of As, P and Sb.
The aforementioned nitride semiconductor light emitting device can be either a laser device or a diode device. Further, such a light emitting device can be preferably employed in an optical apparatus or a semiconductor light emitting apparatus.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 6153010 (2000-11-01), Kiyoku et al.
patent: 6329667 (2001-11-01), Ota et al.
patent: 6335546 (2002-01-01), Tsuda et al.
patent: 6365921 (2002-04-01), Watanabe et al.
patent: 2000124500 (2000-04-01), None
Ito Shigetoshi
Taneya Mototaka
Tsuda Yuhzoh
Yuasa Takayuki
Chaudhuri Olik
Morrison & Foerster / LLP
Sharp Kabushiki Kaisha
Veserman William C
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