Controlling Tunneling Characteristics via Bias Voltage in Bilayer Graphene/WS₂/Metal Heterojunctions

Van der Waals heterojunctions, formed by stacking two-dimensional materials with various structural and electronic properties, opens a new way to design new functional devices for future applications and provides an ideal research platform for exploring novel physical phenomena. In this work, bilayer graphene/WS₂/metal heterojunctions (GWMHs) with vertical architecture were designed and fabricated. The tunneling current-bias voltage (I_t - V) properties of GWMHs can be tuned by 5 × 10⁶ times in magnitude for current increasing from 0.2 nA to 1 mA with applied bias voltage increasing from 10 mV to 2 V. Moreover, the transfer properties of GWMHs exhibit n-type conduction at V = 0.1 V and bipolar conduction at V = 2 V; these findings are explained well by direct tunneling (DT) and Fowler-Nordheim tunneling (FNT), respectively. The results show the great potential of GWMHs for high-power field-effect transistors (FETs) and next-generation logic electronic devices.