Pulsed Laser Deposition and Ionic Liquid Gate Control of Epitaxial Bi2Se3 Thin Films

High-quality epitaxial thin films of the topological insulator Bi2Se3 with atomically flat surfaces have been grown on InP(111)A substrates by means of pulsed laser deposition, which can target a variety of materials for the further chemical tuning of topological insulators. Utilizing an ionic liquid gate structure fabricated on the top of a thin (?6 nm thick) film, we have controlled the sheet carrier density nsheet (up to ?nsheet?1.3?1014 cm-2). The sharp negative magnetoconductance due to the two-dimensional weak antilocalization has been observed and the phase coherence length is modulated with the gate voltage.