12 March 2010 Internal quantum efficiency of m-plane InGaN on Si and GaN
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Proceedings Volume 7602, Gallium Nitride Materials and Devices V; 76021N (2010) https://doi.org/10.1117/12.843727
Event: SPIE OPTO, 2010, San Francisco, California, United States
Abstract
High brightness InGaN light emitting diodes (LEDs) require high quantum efficiency and its retention at high injection levels. The efficiency drop at a high injection levels in InGaN light emitting diodes (LEDs) has been attributed, e.g. to polarization field on polar c-plane InGaN and the heavy effective hole mass which impedes high hole densities and transport in the active quantum wells. In this study, we carried out a comparative investigation of the internal quantum efficiency (IQE) of InGaN active region in LED structures using resonant optical excitation for layers with polar (0001) orientation on c-plane sapphire, and nonpolar (1-100) m-plane orientation, the latter on specially patterned Si and on m-plane bulk GaN. Analysis of the resonant photoluminescence (PL) intensity as a function of the excitation power indicate that at comparable generated carrier concentrations the IQE of the m-plane InGaN on Si is approximately a factor of 2 higher than that of the highly optimized c-plane layer. At the highest laser excitation level employed (corresponding carrier concentration n ~ 1.2 x 1018 cm-3), the m-plane LED structure on Si has an IQE value of approximately 65%. We believe that the m-plane would remain inherently advantageous, particularly at high electrical injection levels, even with respect to highly optimized c-plane varieties. The observations could be attributed to the lack of polarization induced field and the predicted increased optical matrix elements.
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J. Lee, X. Ni, M. Wu, X. Li, R. Shimada, Ü. Özgür, A. A. Baski, H. Morkoç, T. Paskova, G. Mulholland, K. R. Evans, "Internal quantum efficiency of m-plane InGaN on Si and GaN", Proc. SPIE 7602, Gallium Nitride Materials and Devices V, 76021N (12 March 2010); doi: 10.1117/12.843727; https://doi.org/10.1117/12.843727
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