Enhancing the Contact Performance of Two-Dimensional Metals/In₂S₃ Junctions by the Self-Repair of Sulfur Vacancies in Air

Compared with the bulk metals, two-dimensional (2D) materials are more conducive to avoiding the occurrence of the strong Fermi-level pinning effect, showing great application potential in metal–semiconductor junctions (MSJs). However, the van der Waals gap generally produces a large tunneling barrier because of no strong orbital overlap, which leads to a low tunneling probability ( P TB ). Herein, taking ferroelectric In 2 S 3 and 2D metals X 3 C 2 (X = Cd, Hg, Zn) and graphene as examples, we systematically investigate the contact characteristics and P TB . Although Ohmic contact can be achieved via switching the polarization direction of In 2 S 3, the highest P TB is only 18.32% for all Ohmic contact. In fact, compared with intrinsic In 2 S 3, In 2 S 3 with surface sulfur vacancies (SVs) is much more common and should be considered in the preparation and application process. Interestingly, when SVs are exposed to air, we find that oxygen (O 2 ) can effectively repair the SVs via chemical adsorption. Simultaneously, for the self-repair of In 2 S 3 -based MSJs, Ohmic contact remains, and P TB is significantly improved by up to 56.16% by enhancing interlayer interaction and inducing carrier-transport channels. Our results not only provide several potential MSJs but also pave the way for the design of high-performance microelectronic devices.