Gallium K-edge EXAFS study of GaN:Mg films

Ga K-edge extended X-ray absorption fine structure (EXAFS) measurement was employed to investigate the local structure and GaN:Mg films grown my metalorganic vapor phase epitaxy (MOVPE) with various Cp2Mg dopant flow rates using both in-plane and out-of-plane polarization modes of X-rayu. The near edge absorption spectra were found to depend on X-ray polarization strongly for undoped GaN sample and weakly to minutely for heavily Mg-doped and amorphous films. The results indicate Mg incorporation modifies the local structure around the absorber Ga atom and, hence, alters the molecular orbital electron transition of GaN sample. EXAFS analysis shows both vacancy an dMg-interstitial defects contribute to the reduction of coordination numbers along the hexagonal c-axis of GaN:Mg film.