ABSTRACT: The chemical state of N in N-doped amorphous Ge <sub>2</sub> Sb <sub>2</sub> Te <sub>5</sub> (a- GST ) samples with 0–14.3 N at. % doping concentrations was investigated by high-resolution x-ray photoelectron spectroscopy (HRXPS) and Ge K -edge x-ray absorption spectroscopy (XAS). HRXPS showed negligible change in the Te 4d and Sb 4d core-level spectra. In the Ge 3d core-level spectra, a Ge nitride ( Ge N <sub>x</sub>) peak developed at the binding energy of 30.2 eV and increased in intensity as the N-doping concentration increased. Generation of Ge N <sub>x</sub> was confirmed by the Ge K -edge absorption spectra. These results indicate that the N atoms bonded with the Ge atoms to form Ge N <sub>x</sub> , rather than bonding with the Te or Sb atoms. It has been suggested that the formation of Ge nitride results in increased resistance and phase-change temperature.
Applied Physics Letters 09/2007; · 3.84 Impact Factor