Insights into CrS2 monolayer and [formula omitted]-CrS2/[formula omitted]-HfN2 interface for low-power digital and analog nanoelectronics

Abstract

CrS2 monolayers exhibit excellent mechanical, electronic, piezoelectric and thermal properties as compared to other well-known transition metal dichalcogenides. CrS2/HfN2 van der Waals heterobilayer (vdWH) forms a pn-heterojunction where CrS2 and HfN2 act as an n-type and p-type semiconductor respectively, thereby suggesting its utility in nano-electronics and photodetectors. The perpendicular electric field is effective in manipulating band alignments and band gap in CrS2/HfN2 vdWH. Weaker electric field is able to close the band gap in the vdWH relative to CrS2 ML. Therefore, the vdWH may be a promising candidate in low-power analog and digital nano-electronics. Vertical electric field is found to drive the nearly free electron gas (NFEG) states to near the Fermi level in CrS2 ML. These surface states, reported in a few low-dimensional materials, will enhance charge transport and conductivity in electronics. Furthermore, the combined effect of spin–orbit coupling and a small magnitude of vertical electric field helps to reach a type-II band alignment in the CrS2/HfN2 vdWH. It unusually shows a large spin splitting at both conduction and valence band edges, which is very crucial for ambipolar spin transport. This work demonstrates possibilities for futuristic nano-electronic devices based on CrS2 ML & CrS2 based vdWH.