| Luminescence of Highly Excited Nonpolar a-Plane GaN and AlGaN/GaN Multiple Quantum Wells |
| S. Jursenas, E. Kuokstis, S. Miasojedovas, G. Kurilcik, A. Zukauskas Institute of Materials Science and Applied Research, Vilnius University Sauletekio 9-III, 10222 Vilnius, Lithuania C.Q. Chen, J.W. Yang, V. Adivarahan and M. Asif Khan Department of Electrical Engineering, University of South Carolina Columbia, SC 29208, USA |
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| Carrier recombination dynamics in polar and nonpolar GaN epilayers and GaN/AlGaN multiple quantum wells grown over sapphire substrates with various crystallographic orientation were studied under high photoexcitation by 20ps laser pulses. The transient of luminescence featured a significant enhancement in nonradiative recombination of free carriers for nonpolar a-plane GaN epilayers compared to conventional c-plane samples. The epitaxial lateral overgrowth technique was demonstrated to significantly improve the quality of nonpolar a-plane films. This was proved by more than 40-fold increase in luminescence decay time (430ps compared to <=10ps in the ordinary a-plane epilayer). Under high-excitation regime, a complete screening of built-in electric field by free carriers in multiple quantum wells grown on c-plane and r-plane sapphire substrates was achieved. Under such high excitation, luminescence efficiency and carrier lifetime of multiple quantum wells were shown to be determined by the substrate quality. |
| DOI: 10.12693/APhysPolA.105.567 PACS numbers: 78.55.Cr, 73.21.Fg, 72.20.Jv, 78.47.+p |