Topological insulator Bi_2Se_3 thin films as an alternative channel material in metal-oxide-semiconductor field-effect transistors

摘要

Three-dimensional (3-D) topological insulators (TIs) are characterized by the presence of metallic surface states and a bulk band gap. Recently, theoretical and experimental studies have shown an induced gap in the surface state bands of TI thin films. The gap results from interaction of conduction band and valence band surface states from the opposite surfaces of a thin film, and its size is determined by the film thickness. This gap formation could open the possibility of thin-film TI-based metal-oxide-semiconductor field-effect transistors (MOSFETs). Here we explore the performance of MOSFETs based on TI thin films, specifically Bi_2Se_3, using quantum ballistic transport simulations with the tight-binding Hamiltonian in the atomic orbital basis. Our simulations indicate that Bi_2Se_3 MOSFET will be vulnerable to short-channel effects due to the high relative dielectric constant of Bi_2Se_3 (～100) despite its expected excellent electrostatic integrity inherent in a two-dimensional system, and will have other limitations as compared to silicon-based MOSFETs. However, Bi_2Se_3 MOSFETs, and presumably other TI-based MOSFETs, appear to provide reasonable performance that perhaps could provide novel device opportunities when combined with novel TI properties such as spin-polarized surface states.