Tunable ohmic van der Waals-type contacts in monolayer C₃N field-effect transistors

Monolayer (ML) C₃N, a novel two-dimensional flat crystalline material with a suitable bandgap and excellent carrier mobility, is a prospective channel material candidate for next-generation field-effect transistors (FETs). The contact properties of ML C₃N-metal interfaces based on FETs have been comprehensively investigated with metal electrodes (graphene, Ti₂C(OH/F)₂, Zr₂C(OH/F)₂, Au, Ni, Pd, and Pt) by employing ab initio electronic structure calculations and quantum transport simulations. The contact properties of ML C₃N are isotropic along the armchair and zigzag directions except for the case of Au. ML C₃N establishes vertical van der Waals-type ohmic contacts with all the calculated metals except for Zr₂CF₂. The ML C₃N-graphene, -Zr₂CF₂, -Ti₂CF₂, -Pt, -Pd, and -Ni interfaces form p-type lateral ohmic contacts, while the ML C₃N-Ti₂C(OH)₂ and -Zr₂C(OH)₂ interfaces form n-type lateral ohmic contacts. The ohmic contact polarity can be regulated by changing the functional groups of the 2D MXene electrodes. These results provide theoretical insights into the characteristics of ML C₃N-metal interfaces, which are important for choosing suitable electrodes and the design of ML C₃N devices.