Materials World Network: Growth of nonpolar and semipolar GaN on Si and sapphire substrates and investigation of optical processes for high efficiency

The objective of this proposal is to investigate the fundamentals of nonpolar and semipolar GaN growth with the aim of understanding the mechanisms governing defect formation and impurity incorporation as well as processes responsible for radiative recombination. Insight into mechanisms responsible for the defect formation will make it possible to elaborate approaches for reducing defect density and produce the high-optical-quality material for light-emitting diodes and laser diodes with enhanced brightness. The lack of polarization in nonpolar GaN and substantially reduced polarization in semipolar GaN will allow higher recombination efficiencies and eliminate the dependence of emission energy on injection level. The choice of Si and sapphire substrates is motivated by their high quality and wide availability, particularly in the context of cost cutting practices in high brightness LEDs for lighting applications. A multiinstitutional/multidisciplinary program bringing together unique expertise in growth, based at Virginia Commonwealth University, extensive capabilities of precision optical measurements at University of Magdeburg (Germany), and demonstrated experience in theoretical modeling based at University of Montpellier 2 (France) is proposed for understanding the synthesis and properties of transformative nonpolar and semipolar nitride semiconductor structures.