Gate-tunable coherent transport in Se-capped Bi₂Se₃ grown on amorphous SiO₂/Si

A topological insulator (TI) is an exotic material that has a bulk insulating gap and metallic surface states with unique spin-momentum locking characteristics. Despite its various important applications, large scale integration of TI into MOSFET technologies and its coherent transport study are still rarely explored. Here, we report the growth of high quality Bi₂Se₃ thin film on amorphous SiO₂/Si substrate using MBE. By controlling the thickness of the film at ∼7nm and capping the as grown film in situ with a 2nm-thick Se layer, largest electrostatic field effect is obtained and the resistance is changed by almost 300%. More importantly, pronounced gate-tunable weak antilocalization (WAL) is observed, which refers to modulation of α from ∼-0.55 to ∼-0.2 by applying a back gate voltage. The analysis herein suggests that the significant gate-tunable WAL is attributable to the transition from weak disorder into intermediate disorder regime when the Fermi level is shifted downward by increasing the negative back gate voltage. Our findings may pave the ways towards the development of TI-based MOSFET and are promising for the applications of electric-field controlled spintronic and magnetic device.