Insulating Behavior in Ultrathin Bismuth Selenide Field Effect Transistors

Ultrathin (approximately three quintuple layer) field-effect transistors (FETs) of topological insulator Bi2Se3 are prepared by mechanical exfoliation on 300 nm SiO2/Si susbtrates. Temperature- and gate-voltage-dependent conductance measurements show that ultrathin Bi2Se3 FETs are n-type and have a clear OFF state at negative gate voltage, with activated temperature-dependent conductance and energy barriers up to 250 meV.