All-Metallic Vertical Transistors Based on Stacked Dirac Materials

TL;DR

This paper demonstrates that all-metallic vertical heterostructures made from Dirac materials can exhibit high on/off ratios due to a transport gap, enabling their use as transistors without band gap engineering.

Contribution

It introduces a novel all-metallic vertical transistor design based on Dirac materials, showing a significant transport gap and high switching ratio through first-principles simulations.

Findings

Transport gap of over 0.4 eV confirmed

Switching ratio exceeds 10^4

Robust against relative rotation and extendable to twisted bilayer graphene

Abstract

It is a persisting pursuit to use metal as a channel material in a field effect transistor. All metallic transistor can be fabricated from pristine semimetallic Dirac materials (such as graphene, silicene, and germanene), but the on/off current ratio is very low. In a vertical heterostructure composed by two Dirac materials, the Dirac cones of the two materials survive the weak interlayer van der Waals interaction based on density functional theory method, and electron transport from the Dirac cone of one material to the one of the other material is therefore forbidden without assistance of phonon because of momentum mismatch. First-principles quantum transport simulations of the all-metallic vertical Dirac material heterostructure devices confirm the existence of a transport gap of over 0.4 eV, accompanied by a switching ratio of over 104. Such a striking behavior is robust against the relative rotation between the two Dirac materials and can be extended to twisted bilayer graphene. Therefore, all-metallic junction can be a semiconductor and novel avenue is opened up for Dirac material vertical structures in high-performance devices without opening their band gaps.