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

TL;DR

This study explores the growth, defect structures, and electronic properties of disordered ScNx thin films on MgO(100), revealing how temperature influences epitaxial growth, defect formation, and transport behavior.

Contribution

It provides new insights into the real-time growth process and defect-induced disorder in ScNx thin films, highlighting the effects of temperature on epitaxy and electronic properties.

Findings

Epitaxial growth limited to 5 nm at 25°C

Enhanced adatom mobility at higher temperatures up to 25 nm

Presence of N vacancies and O interstitials causes disorder and weak localization

Abstract

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.