Optical Characterization of Double Peak Behavior in {$10\bar{1}1$} Semipolar Light-Emitting Diodes on Miscut $m$-Plane Sapphire Substrates

• Published in: Jpn J Appl Phys 2012-05, Vol.51 (5), p.052101-052101-5
• Main Authors: Choi, Sang-Bae, Bae, Si-Young, Lee, Dong-Seon, Kong, Bo Hyun, Cho, Hyung Koun, Song, Jung-Hoon, Ahn, Byung-Jun, Keading, John F, Nakamura, Shuji, DenBaars, Steven P, Speck, James S
• Format: Article
• Language: English
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.51.052101

$\{10\bar{1}1\}$ semipolar GaN-based light-emitting diodes (LEDs) grown on 1° miscut $m$-plane sapphires substrates via metal organic chemical vapor deposition showed undulated surface morphology with ridges and valleys. On the ridge regions, two dominant emission peaks, one at a shorter wavelength (${\sim}438$ nm) and one at a longer wavelength (${\sim}490$ nm), were observed using electroluminescence and micro-photoluminescence. In the valley regions, the longer peak was observed to be significantly quenched due to the grain boundary. The origin of the longer peak is believed to be not only inhomogeneous distribution of In composition in multiple quantum wells (MQWs) but also strong localization around the ridge region. Moreover, thickness variation of faceted MQWs could be associated with the peak broadening in {$10\bar{1}1$} semipolar LEDs. The results were also confirmed by cathodoluminescence and cross-sectional transmission electron microscopy.