Synchrotron-Based X-ray Spectroscopic Investigation of Nitrogen-Doped Ge-Bi (8.4 at. %)-Te Thin Films during the Amorphous-to-Crystalline Structural Phase Transition

Nitrogen-doped Ge–Bi (8.4 at. %)–Te thin films, which show a rapidly decreasing sheet resistance and NaCl-type X-ray diffraction peaks above 225 °C, were investigated by synchrotron-radiation-based high-resolution X-ray absorption spectroscopy (XAS) and photoelectron spectroscopy (XPS). As the as-deposited film transformed to the crystalline phase in an ultrahigh vacuum ambient, the N 1s and Bi 4f core levels chemically shifted towards higher binding energies (BEs), a lower-BE component developed at the Te 4d core level, and a higher-BE component developed at the Ge 3d core level. The nitrogen molecules, identified by the N K-edge absorption spectra, decreased in intensity and some of them were considered to have decomposed to form a N-content-increased quaternary system.