Spectroscopic studies of InGaN ternary alloys

Abstract

Wurtzite InxGa1-xN films (0.02≲x≲0.14) have been grown by metalorganic vapor phase epitaxy on c-face sapphire. Integrated photoluminescence (PL) intensity and PL peak position have been studied in the 10 to 300 K range. Below 100 K we observe a consecutive red- and blue-shift of the band edge-related PL peak that we assign to radiative recombination localized to conduction band minima. Carriers reach those minima through a thermally excited hopping process. We find the quenching of the PL intensity to be governed by two thermally activated non-radiative recombination channels. The exponential band tail has been studied by photothermal deflection spectroscopy. A pseudo-empirical model is proposed to explain the tail by randomly distributed indium atoms.