Optical properties of GaN grown on Si 111 by gas source molecular beam
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We report a study of the optical properties of GaN grown on Si~111! by gas source molecular beam epitaxy with ammonia. Temperature dependence of edge luminescence was studied in the range of 77–495 K for samples with low background carrier concentrations, as determined by capacitance voltage profiling and Raman spectroscopy, and the results were fitted using Passler’s and Varshni’s models. We also demonstrate strong correlation between electron concentration in GaN and relative Raman intensity of A1 ~longitudinal optical! and E2 2 modes. The binding energy of free excitons is estimated to be 2962 meV. The contributions of different mechanisms to free exciton line broadening are discussed.