Simulation of the EXAFS and Raman spectra of InxGa1-xN utilizing the equation of motion routine of FEFF8.

Abstract

A combined analysis of EXAFS and Raman spectra is applied for the study of InxGa1-xN alloys with 0.3<x<0.5. Alloying causes relaxation of the selection rules resulting in Raman spectra that resemble the vibrational density of states. On the other hand, theoretical simulation of the Raman spectra using the Equation of Motion routine of FEFF8 provides the vibrational component of the Debye-Waller factor (DWF). The static disorder component of the DWFs was obtained by fitting the Ga and In K-edge EXAFS spectra. The analysis revealed that the nearest neighbor distances of the 1st and 2nd shell deviate from the values predicted by the law of Vegard and the virtual crystal approximation. The static disorder in the first nearest neighboring shell (In-N and Ga-N) is null whereas in the cation-cation neighboring shells the static component is generally smaller than the vibrational.