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Fabrication of high performance of AlGaN/GaN-based UV light-emitting diodes

Authors :
Y. Izumi
Shiro Sakai
Tao Wang
Hongdong Li
Jin-Ping Ao
Yuhuai Liu
Jie Bai
Y.B Lee
Source :
Journal of Crystal Growth. 235:177-182
Publication Year :
2002
Publisher :
Elsevier BV, 2002.

Abstract

A high-performance AlGaN/GaN-based ultraviolet (UV) light-emitting diode (LED) is successfully fabricated on sapphire substrate by metal-organic-chemical-vapor-deposition technique. Generally, a p–n junction is grown on a thick GaN layer on sapphire substrate, which results in a strong internal-absorption effect. Simultaneously, a thick AlGaN cladding layer on the GaN layer also easily produces crack. In order to avoid the internal absorption, a thick AlGaN layer is immediately introduced on a thin low-temperature GaN buffer (LT GaN buffer) instead of a thick GaN layer, which successfully avoids crack formation. However, an enhanced lattice-mismatch of AlGaN/LT GaN buffer/sapphire compared with that of GaN/sapphire might result in an enhanced dislocation density, which leads to the degraded performance of UV-LED. An AlGaN/GaN supperlattice that is applied in UV-LED instead of the thick AlGaN layer strongly decreases the dislocation density, confirmed by transmission electron microscope. Furthermore, this AlGaN/GaN supperlattice successfully avoids crack formation. Consequently, the optical power of UV-LED is greatly increased. Based on the above results, we successfully fabricate a crack-free UV-LED with a high performance.

Details

ISSN :
00220248
Volume :
235
Database :
OpenAIRE
Journal :
Journal of Crystal Growth
Accession number :
edsair.doi...........8c18ca287b76ede2458035efe60938d0