Growth and structural characteristics of metastable β-In₂Se₃ thin films on H-terminated Si(111) substrates by molecular beam epitaxy

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.