2D HfN2/graphene interface based Schottky device: Unmatched controllability in electrical contacts and carrier concentration via electrostatic gating and out-of-plane strain

Abstract

Graphene-based van der Waals heterostructure (vdWH) comprising of HfN2monolayer stacked over graphene has been designed and studied based on density functional theory. The vdWH forms an-type Schottky contact with a Schottky barrier height (SBH) of 0.67 eV, while it exhibitsp-type SBH of 0.93 eV. The response of SBH and electrical contact properties to external perturbation, such as, vertical strain and electric field has been investigated thoroughly. Under the application of strain and normal electric field within range of ±0.3 V/Å, the type of electrical contacts, i.e., n/p type Schottky or Ohmic, is found to be interconvertible, while electron/hole doping in graphene is tunable by a doping carrier concentration of up to ~1013 cm−2, which lies between experimentally observed molecular doping (~1012 cm−2) and electrolytic gating (~1014 cm−2). Such an extremely high tunability in electrical contacts, doping carrier concentration along with its excellent optical response in the visible light region shows unrivalled potential of this vdWH in high performance graphene-based futuristic Schottky transistors with high on/off ratio, ultrathin phototransistor with high gain, low-power multivalued optical non volatile memory devices, and nanoelectronics.