Molecular Beam Epitaxial Growth and Characterization of Nanoscale ScGaN

Low-dimensional semiconductor materials, including nanowires, have been an attractive platform for cutting-edge semiconductor device development. On the other hand, scandium (Sc) containing III-nitrides (Sc-III-nitrides) is an emerging material system, offering not only novel ferroelectric devices but also potentially multifunctional devices in a single-material platform. In this study, we investigate nanoscale ScxGa1-xN (ScGaN) hosted in GaN nanowires grown by molecular beam epitaxy on Si substrate. The major findings are (1) Within each ScGaN insert layer, the Sc content is not uniform as indicated by transmission electron microscopy studies, suggesting the formation of ScGaN nanoclusters with different Sc contents; (2) ScGaN shell is formed spontaneously; and (3) Zincblende phase is observed in the ScGaN insert layers although the estimated average Sc content is only around x = 0.16. The possible mechanisms related to these findings are also discussed. These unveiled correlated epitaxial and structural properties could help in the development of Sc-III-nitride nanowire devices.