Positron structural analysis of ScN films deposited on MgO substrate

Abstract

Scandium nitride (ScN) is a semiconductor with a rocksalt-structure that has attracted attention for its potential applications in thermoelectric energy conversion devices, as a semiconducting component in epitaxial metal/semiconductor superlattices. Two ScN films of 118 nm and 950 nm thicknesses were deposited at the same conditions on MgO (001) substrate by reactive magnetron sputtering. Poly-orientation of films was observed with first an epitaxial growth on MgO and then a change in the orientation growth due to the decrease of the adatom mobility during the film growth. Positron lifetime measurements showed a high concentration of nitrogen vacancies in both films with a slightly higher concentration for the thicker ScN film. Presence of nitrogen vacancies explains the values of direct band gaps of 2:53±0:01 eV, and 2:56±0:01 eV which has been measured on ScN films of 118 nm and 950 nm thicknesses, respectively.