Two-dimensional MoTe2/SnSe2 van der Waals heterostructures for tunnel-FET applications

Abstract

Two-dimensional (2D) van der Waals heterostructures (vdWHs) are attractive candidates for realizing tunnel field-effect transistors (TFETs) for low-power applications. In this work, using first-principles calculations based on density functional theory (DFT), we explore heterostructures composed of 2D $\mathrm{Mo}{\mathrm{Te}}_{2}$ and $\mathrm{Sn}{\mathrm{Se}}_{2}$. Our calculations reveal that upon forming the heterostructures, the valence band top of $\mathrm{Mo}{\mathrm{Te}}_{2}$ and the conduction band bottom of $\mathrm{Sn}{\mathrm{Se}}_{2}$ are almost aligned, forming the nearly broken-gap or type-III band alignment which is highly promising for TFETs. Interestingly, we find that the band alignment can be tuned by applying external electric fields. For positive electric fields, $\mathrm{Mo}{\mathrm{Te}}_{2}$ $(\mathrm{Sn}{\mathrm{Se}}_{2})$ band-edge positions are shifted upward (downward) with respect to the Fermi level, and more electrons are expected to tunnel from $\mathrm{Mo}{\mathrm{Te}}_{2}$ to $\mathrm{Sn}{\mathrm{Se}}_{2}$. Overall, our simulations provide fundamental insights into the electronic properties of $\mathrm{Mo}{\mathrm{Te}}_{2}/\mathrm{Sn}{\mathrm{Se}}_{2}$ stacks, and pave the way for the design and fabrication of future $\mathrm{Mo}{\mathrm{Te}}_{2}/\mathrm{Sn}{\mathrm{Se}}_{2}$-based TFETs.