Nitrogen contribution to N-doped GeTe (N: 8.4 at.%) in the structural phase transition

Chemical states of N-doped GeTe (N: 8.4 at.%) thin film (NGT) in structural phase transition were investigated by near-edge x-ray absorption of fine structure and high-resolution x-ray photoelectron spectroscopy with synchrotron radiation. We found the NaCl-like structure in NGT by x-ray diffraction at around 300 °C. Preparatory to the analysis of chemical states, after mild Ne + sputtering we obtained clean amorphous NGT, which showed the N 2 vibration mode peak in the N K-edge absorption spectrum. After annealing, the N 2 molecular peak disappeared completely and we assumed that nitrogen was contributed only to the Ge atom in structural phase transition by analyzing Ge 3 d and Te 4 d core-levels. ► We performed NEXAFS and HRXPS experiments on N-doped GeTe (N: 8.4 at.%). ► We found the N 2 molecular vibration mode peak in the absorption spectra of the amorphous phase. ► The vibration mode peak completely disappeared after annealing. ► We confirmed the chemical states of Te–GeN x ( x > 1), N–Ge and N–Ge–Te. ► The nitrogen contribution to the N-doped GeTe system, in the structural transition, was incorporated only with Ge.