Interface effects in molecular beam epitaxy of SrMnSb2 on InAs and GaSb: segregation and endotaxy

Abstract

Epitaxial growth of the topological semimetal SrMnSb₂ is demonstrated using InAs and GaSb substrates. The growth is studied by reflection high energy electron diffraction, X-ray photoemission spectroscopy and electron microscopy. The epitaxial orientation is SrMnSb₂ (001)||III–V (001), with the epilayer <010> axes parallel to substrate <110>. The relaxed in-plane lattice parameter of the epilayer depends on the vicinal miscut of the substrate and results in an overall volume expansion of the unit cell compared to bulk crystals, along with a possible lifting of the bulk orthorhombic distortion. Segregation of substrate atoms through the growing film is observed, along with Mn-driven endotaxial growth of secondary phases. Interface control methods to suppress endotaxial growth are discussed.