Field effect in stacked van der Waals heterostructures: Stacking sequence matters

TL;DR

This study demonstrates that the electronic behavior of stacked van der Waals heterostructures, specifically graphene-contacted MoS2 transistors, critically depends on stacking sequence, influencing contact resistance and device performance.

Contribution

First-principles quantum transport simulations reveal the impact of stacking order on the gate-induced electric field response in 2D heterostructure devices.

Findings

Stacking sequence affects transistor behavior.

Contact resistance varies with stacking configuration.

Design rules for 2D device optimization are established.

Abstract

Stacked van der Waals (vdW) heterostructures where semi-conducting two-dimensional (2D) materials are contacted by overlayed graphene electrodes enable atomically-thin, flexible electronics. We use first-principles quantum transport simulations of graphene-contacted MoS2 devices to show how the transistor effect critically depends on the stacking configuration relative to the gate electrode. We can trace this behavior to the stacking-dependent response of the contact region to the capacitive electric field induced by the gate. The contact resistance is a central parameter and our observation establish an important design rule for devices based on 2D atomic crystals.