The dimensional crossover of quantum transport properties in few-layered BiSe thin films.

Topological insulator bismuth selenide (BiSe) thin films with a thickness of 6.0 quintuple layers (QL) to 23 QL are deposited using pulsed laser deposition (PLD). The arithmetical mean deviation of the roughness ( ) of these films is less than 0.5 nm, and the root square mean deviation of the roughness ( ) of these films is less than 0.6 nm. Two-dimensional localization and weak antilocalization are observed in the BiSe thin films approaching 6.0 nm, and the origin of weak localization should be a 2D electron gas resulting from the split bulk state. Localization introduced by electron-electron interaction (EEI) is revealed by the temperature dependence of the conductivity. The enhanced contribution of three-dimensional EEI and electron-phonon interaction in the electron dephasing process is found by increasing the thickness. Considering the advantage of stoichiometric transfer in PLD, it is believed that the high quality BiSe thin films might provide more paths for doping and multilayered devices.