Nitrogen K-edge EXAFS measurements on Mg- and Si-doped GaN

Prior to the analysis, the EXAFS spectra were normalised to the flux of the monochromator by division with the electron yield spectrum from a clean Si wafer. The normalised EXAFS spectra were subjected to subtraction of the atomic absorption using the AUTOBK program (Mustre de Leon et al., 1991). The spectra were corrected for self-absorption effects in the k space using the procedure described previously (Katsikini et al., 1997). A model for hexagonal GaN (a=3.18 Angstrom, c=5.168 Angstrom) was constructed using the FEFF6 code (Mustre de Leon et al., 1991). The initial values for the Debye-Waller (BW) factors were calculated using the correlated Debye model (Sevillano et al., 1979) and a Debye temperature of 600K.