Investigations on Strained AlGaN/GaN/Sapphire and GaInN Multi-Quantum-Well Surface LEDs Using AlGaN/GaN Bragg Reflectors

Hiroyasu ISHIKAWA  Naoyuki NAKADA  Masaharu NAKAJI  Guang-Yuan ZHAO  Takashi EGAWA  Takashi JIMBO  Masayoshi UMENO  

IEICE TRANSACTIONS on Electronics   Vol.E83-C   No.4   pp.591-597
Publication Date: 2000/04/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Blue Laser Diodes and Related Devices/Technologies)
light emitting diode (LED),  distributed Bragg reflector (DBR),  GaN,  AlGaN,  GaInN,  

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Investigations were carried out on metalorganic-chemical-vapor-deposition (MOCVD)-grown strained AlGaN/ GaN/sapphire structures using X-ray diffratometry. While AlGaN with lower AlN molar fraction (< 0.1) is under the in-plane compressive stress, it is under the in-plane tensile stress with high AlN molar fraction (> 0.1). Though tensile stress caused the cracks in AlGaN layer with high AlN molar fraction, we found that the cracks dramatically reduced when the GaN layer quality was not good. Using this technique, we fabricated a GaInN multi-quantum-well (MQW) surface emitting diodes were fabricated on 15 pairs of AlGaN/GaN distributed Bragg reflector (DBR) structures. The reflectivity of 15 pairs of AlGaN/GaN DBR structure has been shown as 75% at 435 nm. Considerably higher output power (1.5 times) has been observed for DBR based GaInN MQW LED when compared with non-DBR based MQW structures.