Hydrogen bonding-driven Ohmic contact in Sc2CT2 (T=H, F, OH) based field-effect transistors

With the continuous miniaturization of transistors, atomically thin two-dimensional (2D) semiconductor materials have shown significant promise for developing advanced electronic devices. However, the significant Schottky barrier arising from the work function difference between metal electrodes and 2D semiconductors limits the carrier injection efficiency. In this study, by combining electronic structure calculations and quantum transport simulations, we thoroughly investigate the interface characteristics of field-effect transistors based on Sc2CT2 (T = H, F, OH) with MoSH as the electrode as an example to achieve Ohmic contact for 2D semiconductors. It is highlighted that the pristine band structures of Sc2CH2 are destroyed in MoSH/Sc2CH2 heterojunctions due to the strong interlayer coupling. Notably, O–H⋯S hydrogen bonding at the interface enables Sc2C(OH)2 to form ultra-clean Ohmic contact and quasi-Ohmic contact with HMoS, respectively, in the vertical and lateral directions, significantly improving electron injection efficiency. Furthermore, Ohmic contact can be formed in SMoH/Sc2CF2 heterojunction by modulating interlayer distance and applying biaxial strain. These findings offer significant theoretical insights for attaining Ohmic contact in electronic devices utilizing 2D semiconductors.