Independent Band Modulation in 2D van der Waals Heterostructures via a Novel Device Architecture

Benefiting from the technique of vertically stacking 2D layered materials (2DLMs), an advanced novel device architecture based on a top-gated MoS₂/WSe₂ van der Waals (vdWs) heterostructure is designed. By adopting a self-aligned metal screening layer (Pd) to the WSe₂ channel, a fixed p-doped state of the WSe₂ as well as an independent doping control of the MoS₂ channel can be achieved, thus guaranteeing an effective energy-band offset modulation and large through current. In such a device, under specific top-gate voltages, a sharp PN junction forms at the edge of the Pd layer and can be effectively manipulated. By varying top-gate voltages, the device can be operated under both quasi-Esaki diode and unipolar-Zener diode modes with tunable current modulations. A maximum gate-coupling efficiency as high as ≈90% and a subthreshold swing smaller than 60 mV dec^-1 can be achieved under the band-to-band tunneling regime. The superiority of the proposed device architecture is also confirmed by comparison with a traditional heterostructure device. This work demonstrates the feasibility of a new device structure based on vdWs heterostructures and its potential in future low-power electronic and optoelectronic device applications.