Hisashi Yamada1, Kenji Iso1, Makoto Saitô1, Hirohiko Hirasawa1, Natalie Fellows1, Hisashi Masui1, Kenji Fujito2, James S. Speck1, Steven P. DenBaars1, Shuji Nakamura1
1Materials Department, University of California, Santa Barbara CA, 93106, USA
2Optoelectronics Laboratory, Mitsubishi Chemical Co., Ltd. 1000 Higashi-Mamiana, Ushiku, Ibaraki 300-1295, Japan
Tóm tắt
AbstractInGaN/GaN‐based light emitting diodes (LEDs) grown on m ‐plane, a ‐plane and off‐axis between m ‐ and a ‐plane GaN bulk substrates were investigated. A smooth surface was obtained when a ‐plane substrate was applied; however, large amounts of defects were observed. Photoluminescence measurements of the LEDs with a well thickness of 2.5 nm revealed that all the LEDs showed the peak emission wavelength at 389 nm. The PL intensity of the a ‐plane LED is one order of magnitude lower than that of the m ‐plane LED. The a ‐plane LEDs showed significant lower electroluminescence output powers than m ‐plane LEDs, suggesting that excitons are trapped by the defects, which act as non‐radiative recombination centers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
