Theoretical Study of Intercalation Effects: Graphene and hBN Layers in Metal and Monolayer Black Phosphorus Contacts

The gap state caused by the metal is the main factor causing the high resistance between the metal and the semiconductor, which also hinders the electrical modulation at the heterojunction interface. This issue can be alleviated by inserting an insulating layer between the metal and the semiconductor. However, theoretical studies on the effect of the insertion layer on the interface and transport properties are not sufficient. In this study, we constructed a metal–insulator–semiconductor (MIS) heterojunction by vertically stacking metal, insertion layer (graphene, hBN), and black phosphorus. A tunable interfacial barrier was achieved through van der Waals contacts, which selectively forms Ohmic or Schottky contacts. It has also been found that uniaxial strain can effectively reduce the tunneling barrier, especially for Cu and Pt. Additionally, the insertion layer can reduce the effective mass of holes, which facilitates the formation of p-type semiconductors and enhances the transport properties. By adjusting the thickness of graphene, the polarity of the carriers can be altered and electrical modulation can be achieved. In addition, we have investigated the mechanism of interlayer interactions underlying the process. This work provides a comprehensive understanding of insertion effects in MIS, paving the way for potential technological applications based on vertically stacked nanomaterials.