Raman scattering study of InGaN ternary alloys grown by MOVPE on (0001) sapphire substrates

摘要

We have studied the asymmetric broadening of the Raman spectra of In/sub x/Ga/sub 1-x/N grown on sapphire substrates with the aid of the spatial correlation model. The asymmetric broadening of E/sub 2/ phonon mode is enhanced in the region of immiscibility and enhanced by increasing the indium molar fraction. The correlation length, which corresponds to the decay length of E/sub 2/ phonon mode was estimated for the first time. It was of the order of 6/spl sim/10 nm, which is of the same order of magnitude as the size of the columnar structure suggested by TEM analyses.