Tuning Chemical Potential in the Dirac Cone by Compositional Engineering

Abstract

We report the successful formation of bulk insulating ternary topological insulators candidate Bi2Se2Te (BST) by pulsed laser deposition technique. The films were deposited with sequential ablation of separate Bi2Se3 (BS) and Bi2Te3 (BT) targets. From the X-ray diffraction analysis and temperature dependent resistivity we were able to conclude that the as grown thin films have ordered chalcogen layers and the chemical potential in these thin films lie in the bulk gap. To realize entirely topological transport for any device applications it is essential to tune the chemical potential in the bulk gap of the Dirac cone. Magnetotransport data exhibits pronounced two dimensional weak-antilocalization behavior (WAL) at low temperatures. BS and BT thin films do not exhibit topological transport as the chemical potential does not lie entirely in the bulk gap. It was found that BST thin films grown with this cost effective and simple yet elegant technique using double target can be used to deposit quaternary TI thin films, thereby tuning the chemical potential at will in the gap.

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