We report the molecular beam epitaxial growth and characterization of wurtzite InScN thin films. We find that wurtzite InScN can be grown on GaN substrates under metal-rich conditions, resulting in smooth surfaces with 1 nm roughness and a two-dimensional growth mode. We further find that InScN can be stabilized in the wurtzite crystalline phase for Sc content up to at least 10.4%. We measure and report the lattice parameters of wurtzite InScN as a function of Sc content and find that between ∼5% and 8% Sc mole fraction InScN has a similar a lattice constant to InN. The c/a ratio deviates from the ideal tetrahedral value of 1.633 as Sc content increases. The optical absorption edge of wurtzite InScN monotonically increases over a Sc content range of 0%–10.4% from 0.8 to 1.05 eV, accompanied by a shift in the peak index of refraction and extinction coefficient. The E2high Raman peak of InScN shows negligible shift with increasing Sc content compared to a gradual increase in the A1 (LO) peak position. These fundamental observations can facilitate the future design of InN-based devices.
Lonergan et al. (Mon,) studied this question.