  Tunnel field effect transistors (TFETs) based on vertical stacking of two
dimensional materials are of interest for low-power logic devices. The
monolayer transition metal dichalcogenides (TMDs) with sizable band gaps show
promise in building p-n junctions (couples) for TFET applications. Band
alignment information is essential for realizing broken gap junctions with
excellent electron tunneling efficiencies. Promising couples composed of
monolayer TMDs are suggested to be VIB-MeX2 (Me= W, Mo; X= Te, Se) as the
n-type source and IVB-MeX2 (Me = Zr, Hf; X= S, Se) as the p-type drain by
density functional theory calculations.
