Growth of wurtzite ScxAl1−xN (x < 0.23) by plasma-assisted molecular-beam epitaxy on cplane GaN at high temperatures significantly alters the extracted lattice constants of the material
due to defects likely associated with remnant phases. In contrast, ScAlN grown below a
composition-dependent threshold temperature exhibits uniform alloy distribution, reduced defect
density, and atomic-step surface morphology. The c-plane lattice constant of this low-temperature
ScAlN varies with composition as expected from previous theoretical calculations and can be
used to reliably estimate alloy composition. Moreover, lattice-matched Sc0.18Al0.82N/GaN multiquantum wells grown under these conditions display strong and narrow near-infrared
intersubband absorption lines that confirm advantageous optical and electronic properties.