  Three-dimensional (3-D) topological insulators (TI) 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 (CB) and
valence band (VB) 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 Bi2Se3, using quantum ballistic transport simulations
with the tight-binding Hamiltonian in the atomic orbital basis. Our simulations
indicate that Bi2Se3 MOSFET will be vulnerable to short-channel effects due to
the high relative dielectric constant of Bi2Se3(~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,
Bi2Se3 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.
