Emerging 2D materials for tunneling field effect transistors

Abstract

This work focuses on understanding the electronic properties of materials to enhance the performance of Tunnel Field Effect Transistor (TFET) through Density Functional Theory (DFT) simulations. Material selection prefers a p-type material with in-plane high density of state (DOS) (and low out-of-plane effective mass, m*, where defined for many layer systems), and high valence band maxima (VBM) energy stacked with an n-type material with low conduction band minimum (CBM) energy (large electron affinity (EA)) that creates a broken or nearly broken band alignment and has low lattice mismatch. SnSe2 is well-suited for an n-type 2D material due to high EA, while WSe2, Black phosphorous (BP) and SnSe are explored for p-type materials. Bilayers consisting of monolayers of WSe2 and SnSe2 show a staggered but nearly broken band alignment (gap of 24 meV) and a high valence band DOS for WSe2. BP-SnSe2 shows a broken band alignment and benefits from a low lattice mismatch. SnSe-SnSe2 shows the highest chemical stability, an optimal performance in terms of DOS of SnSe, tunability with an external field, and high VBM that also leads to a broken band alignment.