Magnitude of the Current in Two-Dimensional Interlayer Tunneling Devices

TL;DR

This study uses first-principles calculations to analyze tunneling currents in graphene/h-BN/graphene devices, revealing discrepancies with experiments that are reduced by considering realistic band gaps and misalignments.

Contribution

It provides a detailed theoretical analysis of tunneling currents in 2D heterostructures, incorporating misalignment effects and realistic band gaps to improve agreement with experimental data.

Findings

Predicted currents are about 15 times larger than experimental values without corrections.

Including realistic h-BN band gaps reduces the discrepancy to 2.5 times.

Misalignment effects significantly influence the tunneling current magnitude.

Abstract

Using the Bardeen tunneling method with first-principles wave functions, computations are made of the tunneling current in graphene / hexagonal-boron-nitride / graphene (G/h-BN/G) vertical structures. Detailed comparison with prior experimental results is made, focusing on the magnitude of the achievable tunnel current. With inclusion of the effects of translational and rotational misalignment of the graphene and the h-BN, predicted currents are found to be about 15x larger than experimental values. A reduction in this discrepancy, to a factor of 2.5x, is achieved by utilizing a realistic size for the band gap of the h-BN, hence affecting the exponential decay constant for the tunneling.