A new device architecture based on two dimensional van der Waals heterostructures
Van der Waals two-dimensional layered materials (2DLMs) have been demonstrated as a promising candidates for band-to-band-tunneling transistors. Here we bring forward a new device architecture of top-gated MoS2/WSe2 van der Waals heterostructures device by inserting a self-aligned metal film functioning as a screening layer. Such device architecture could realize independent control of carrier concentration and more efficient band alignment in MoS2 while the WSe2 side kept constant. Current modulation can be achieved by tuning top-gate voltage, and device can be either operated under a rectifier mode or a band-to-band tunneling (BTBT) mode. A gate coupling efficiency of ∼42% is obtained at large negative gate voltage and saturates by increasing gate voltage due to high electron density of states (DOS) at the conduction band edge of MoS2, which is indicative of achieving independent manipulation of band alignment and carrier density of MoS2. A high on/off ratio (>105) and small subthreshold wing (ã75mV/dec) are obtained under band-to-band tunneling mode. We also adapt this structure to graphene barrister by adding a Ni film on the MoS2 portion as screening layer Our work demonstrates the feasibility of a new device structure based on van der Waals heterostructures and its application in future low power electronic devices.