Insulating behavior in ultra-thin bismuth selenide field effect   transistors
  Ultrathin (~3 quintuple layer) field-effect transistors (FETs) of topological insulator Bi2Se3 are prepared by mechanical exfoliation on 300nm 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. 
Sungjae Cho, Nicholas P. Butch, Johnpierre Paglione, and Michael S.   Fuhrer
cond-mat.mes-hall cond-mat.mtrl-sci