Utilizing the Janus MoSSe surface polarization in designing complementary metal-oxide-semiconductor field-effect transistors

Janus transition metal dichalcogenides (JTMDs) have attracted much attention because of their outstanding electronic and optical properties. The additional out-of-plane dipole in JTMDs can form $n$- and $p$-like contacts, and this may be used in device applications, such as pin diodes and photovoltaic cells. In this study, we exploit this property to design $n$- and $p$-type metal-oxide-semiconductor field-effect transistors (MOSFETs). First, we use density-functional-theory calculations to study the inherent dipole field strength in the trilayer JTMD $\mathrm{Mo}\mathrm{S}\mathrm{Se}$. The intrinsic dipole of $\mathrm{Mo}\mathrm{S}\mathrm{Se}$ causes band bending at both the metal/$\mathrm{SMo}\mathrm{Se}$ and $\mathrm{SMo}\mathrm{Se}$/metal interfaces, resulting in electron and hole accumulation to form $p$-type, $n$-type, and even Ohmic contact regions. We incorporate this property into a two-dimensional finite-element-based Poisson-drift-diffusion solver to perform simulations, based on which we design complementary MOSFETs. Our results demonstrate that JTMDs can be used to make $n$- and $p$-MOSFETs in the same layer without the need for any extra doping.