High throughput screening of Ohmic contacts in 2D metal-semiconductor van der Waals heterojunctions

High-throughput DFT calculations have been employed to investigate the contact formation of 1297 semiconducting two-dimensional (2D) monolayers from the C2DB as channel materials with three 2D metal monolayers: PdTe₂, NbSe₂, and ScS₂. van der Waals heterojunctions (vdWHs), consisting of a single-layer semiconductor and a metal monolayer, constitute metal-semiconductor 2D contacts. A total of 760, 362, and 148 monolayers were found to form n-type Ohmic contacts, while 53, 14, and 999 formed p-type Ohmic contacts with these metal monolayers, respectively, in the Anderson limit (i.e., without forming the actual vdWH). Hexagonal monolayers with minimal lattice mismatch were selected to form vdWHs, ensuring stable interfaces while preserving electronic properties. HSE06-based DFT calculations confirm both the retention and type (p or n) of Ohmic contact. The electrostatic potential difference at the interface, interfacial charge transfer, and interfacial dipole moment are identified as critical factors in determining the contact type (n-type or p-type) and the corresponding Schottky barrier height. These findings provide valuable insights for selecting 2D materials to achieve Ohmic contacts in nanodevices, enabling the development of more efficient and reliable electronic components.