Abstract
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.
Highlights
WSe2 van der Waals heterostructure is designed
2) Such structure enables the scale-down of the TFET channel length, because one of the components (e.g., WSe2 in the proposed device) is totally covered under the screening metal film, which suggests that the device channel length is the same as in regular 2D layered materials (2DLMs)-FETs
In the proposed device architecture, the additional Pd film acts as a screening layer, and as the contact metal that induces p-doping of the WSe2 portion
Summary
2) Such structure enables the scale-down of the TFET channel length, because one of the components (e.g., WSe2 in the proposed device) is totally covered under the screening metal film, which suggests that the device channel length is the same as in regular 2DLM-FETs. to eliminate the Fermi pinning effect at the MoS2–metal interface, the contact of the proposed device can be improved by transferring graphene onto the MoS2 end, which improves contact resistance and enables more flexible modulation of the MoS2 energy band by the gate electrical field
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