Raman analysis of the configurational disorder in AlxGa1−xN films

Raman analysis of the $\text{E2}$ mode of ${\mathrm{Al}}_x{\mathrm{Ga}}_{\text{1−x}}\mathrm{N}$ in the composition range $\text{0⩽x⩽1}$ is presented. The line shape was observed to exhibit a significant asymmetry and broadening toward the high energy range. The spatial correlation model is discussed, and is shown to account for the line shape. The model calculations also indicate the lack of a long-range order in the chemical vapor deposition alloys. These results were confirmed by x-ray scattering: the relative intensity of the superlattice line was found to be negligible. The line broadening of the $\text{E2}$ mode was found to exhibit a maximum at a composition $\text{x≅0.5}$ indicative of a random disordered alloy system.