Studies of Stokes shift in Inx Ga1-x N alloys

InGaN ternary alloys have been studied with photoluminescence, photoluminescence excitation spectroscopy, scanning electron microscopy, and cathodoluminescence spectroscopy. The relatively large Stokes shift observed in the photoluminescence and photoluminescence excitation spectroscopy has been found to be consistent with previous results reported in the literature. By correlating our experimental findings and others reported in the literature with those of scanning electron microscopy and cathodoluminescence spectroscopy, we conclude that the physical origin of the Stokes shift in InGaN ternary alloy system is primarily due to the effects of alloy composition fluctuations. A plausible model responsible for the observed Stokes shift is proposed.