Angle resolved NEXAFS spectra of hexagonal and cubic GaN

Phase stabilised cubic and hexagonal GaN thin films, grown by MBE, are studied using angle (theta) resolved NEXAFS measurements at the N-K-edge. It is demonstrated that the energy positions and intensities of the characteristic NEXAFS resonances depend on the crystal symmetry and can be used as a fingerprint of the symmetry of the examined crystal, Deviations from the cubic or hexagonal symmetries are clearly detectable since they lead to a shift in the resonances of the NEXAFS structure and a characteristic intensity angular dependence. Based on the above results, a formalization for a quantitative assessment of the cubic and hexagonal contributions in a mixed crystal is discussed.