Interplay of Al and Bi Incorporation in AlInSbBi

AlInSbBi is an interesting yet underexplored material system with potential applications in devices operating in the infrared range. Thus far, its development has been hindered by the challenges associated with growing Bi-containing III–V alloys. In this study, we demonstrate the first molecular beam epitaxial growth of AlInSbBi and identify a kinetically limited growth regime for the quaternary. At low Al concentrations, Bi incorporation was limited to approximately 0.4% under a wide array of growth conditions, with excess Bi precipitating out into droplets on the surface of the film. However, increasing the Al concentration in the host matrix allowed for higher Bi incorporation, possibly due to decreased local strain or the reactivity of Al. Rutherford backscattering spectrometry measurements confirmed that AlInSbBi films containing 55% Al enabled record high Bi incorporation up to 7.8%. Atomic force microscopy scans revealed the presence of Bi droplets, suggesting saturation under these growth conditions. Altogether, these findings highlight the underexplored potential of AlInSbBi, which may contribute significantly to future optoelectronic devices as a wide bandgap barrier material with tunable lattice constants and band alignments.