Growth and structural characteristics of metastable β-In2Se3 thin films on H-terminated Si(111) substrates by molecular beam epitaxy**Project supported by the National Key Research and Development Program of China (Grant Nos. 2018YFA0306102 and 2018YFA0306703), the National Natural Science Foundation of China (Grant Nos. 61474014 and U1601208), and the Sichuan Science and Technology Program, China (Grant Nos. 2019YJ0202 and 20GJHZ0229).

Abstract

Epitaxial growth and structural characteristics of metastable β-In2Se3 thin films on H-terminated Si(111) substrates are studied. The In2Se3 thin films grown below the β-to-α phase transition temperature (453 K) are characterized to be strained β-In2Se3 mixed with significant γ-In2Se3 phases. The pure-phased single-crystalline β-In2Se3 can be reproducibly achieved by in situ annealing the as-deposited poly-crystalline In2Se3 within the phase equilibrium temperature window of β-In2Se3. It is suggeted that the observed γ-to-β phase transition triggered by quite a low annealing temperature should be a rather lowered phase transition barrier of the epitaxy-stabilized In2Se3 thin-film system at a state far from thermodynamic equilibrium.