Rock-Salt ScN(113) Layers Grown on AlN(112̅2) by Plasma-Assisted Molecular Beam Epitaxy

Transition-metal nitrides constitute a versatile class of materials with diverse properties and wide-ranging applications. Exploring surface orientations and uncovering distinctive properties can enable innovative material configurations with tailored functionalities for device integration. Here, we report the growth and characterization of (85–210) nm-thick unintentionally doped ScN layers on AlN(112̅2)/Al2O3(101̅0) templates via plasma-assisted molecular beam epitaxy. X-ray diffractometry and transmission electron microscopy confirm a pure (113) surface orientation with rotational twins. Two distinct in-plane relationships between ScN(113) and AlN(112̅2) have been identified: the dominant [11̅0]ScN || [1̅1̅23]AlN and [332̅]ScN || [11̅00]AlN (under tensile compression) and the less prevalent [1̅2̅1]ScN || [11̅00]AlN and [74̅1̅]ScN || [1̅1̅23]AlN (under biaxial compression). Broad photoluminescence spectra with a peak emission energy of ≈2.16 eV originate from the lowest direct gap at the X point of the ScN band structure. Temperature-dependent Hall-effect measurements (4–380 K) reveal that impurity band conduction dominates. The electron mobility is primarily limited by optical phonon scattering, characterized by an effective phonon energy of (60 ± 3) meV.