Raman analysis of the configurational disorder in AlxGa1-xN films

Raman analysis of the E2 mode of AlxGa1-xN in the composition range 0 less than or equal to x less than or equal to 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 E2 mode was found to exhibit a maximum at a composition x congruent to 0.5 indicative of a random disordered alloy system. (C) 1997 American Institute of Physics.