The heterostructure and electrical properties of Sb2Se3/Bi2Se3 grown by molecular beam epitaxy

Abstract

We report the growth and characterization of Sb2Se3/Bi2Se3 bilayer films fabricated by molecular beam epitaxy. High quality heterostructures are obtained as evidenced from the X-ray diffraction (XRD), atomic force microscopy and high-resolution transmission electron microscopic (HRTEM) analysis. Interestingly, Sb2Se3 grows as a (120) hexacrystal film in orthorhombic phase on rhombohedral Bi2Se3 (0001) plane, as verified by the out-of-plane and in-plane XRD scans. The cross-sectional TEM studies indicate a sharp interface between Sb2Se3 and Bi2Se3, which is important for the protection of surface states Bi2Se3. The ultraviolet photoelectron spectroscopy indicates that the Fermi level located 0.95 eV above the valence band maximum in Sb2Se3. The insulating nature of Sb2Se3 is confirmed by the nonlinear current-voltage curve via the vertical junction electrical measurement. By four point probe measurements, we confirm the charge transfer effect from Sb2Se3 into Bi2Se3, and such effect can be reduced in the Sb2Se3/(Bi0.7Sb0.3)2Se3 bilayer. This work opens a new avenue for the synthesis of multilayers consisting of topological insulators and ordinary insulator, which is important for harvesting of the multiple surface states for advanced electronic and spintronic applications.