Ge nitride formation in N-doped amorphous Ge₂Sb ₂Te₅

The chemical state of N in N-doped amorphous Ge2 Sb2 Te5 (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 Nx) peak developed at the binding energy of 30.2 eV and increased in intensity as the N-doping concentration increased. Generation of Ge Nx was confirmed by the Ge K -edge absorption spectra. These results indicate that the N atoms bonded with the Ge atoms to form Ge Nx, 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.