Computational discovery of metallic MBenes for two-dimensional semiconductor contacts approaching the quantum limit

The realization of ultralow-resistance contacts in two-dimensional semiconductors such as transition metal dichalcogenides (TMDs) is pivotal for advancing transistor scaling toward the end of technology roadmap. In this work, by means of high-throughput first-principles calculations, we identify that highly stable two-dimensional metallic MBenes with large abundance of density of states are potential for achieving low-resistance MBene-TMD contacts at the quantum limit. We reveal that local built-in electric field at MBene-MoS2 interfaces driven by interfacial polarization enables tunable band shift of MoS2 channel, which allows for obtaining p-type Ohmic contact. The strong van der Waals interactions between MBenes and MoS2 induces a delicate balance between the Fermi-level pinning and carrier tunneling efficiency, resulting in ultralow contact resistance down to 41.6 Ω μm. The contact performance of screened Nb2BO2-MoS2 and Nb2B(OH)2-MoS2 junctions can be competed with previous records using semimetals Sb and Bi as the contacts of MoS2 devices.