Stranski-Krastanov Growth of Disordered ScNx Thin Films on MgO(100): Influence of Defect Densities on Electronic Structure and Transport Properties

We report a nascent real time Stranski-Krastanov growth of reactively sputtered ScNx thin films on MgO(100). The epitaxial growth was limited to 5 nm at a substrate temperature (Ts) of 25 C while the self-sustaining epitaxial nature along the [100] azimuth was retained up to 25 nm in Ts = 250 and 500 C samples due to enhanced adatom mobility. At Ts = 700 C, the film showed half order in-situ RHEED pattern, with forbidden (hkl) planes indicating N deficient hcp Sc-N phase. Presence of defect densities i.e., N vacancies and O interstitials leads to a disorder in ScNx system with weak localization effect and appearance of Raman relaxed first order transverse and longitudinal optical phonon modes and further leads to metal like Seebeck coefficient. Higher grain boundaries at Ts = 25 C and higher N out-diffusion at Ts = 700 C paves way for incorporation of higher oxygen interstitial in these samples.