Negative Differential Resistance in Graphene Boron Nitride Heterostructure Controlled by Twist and Phonon-Scattering

TL;DR

This study models electron transport in a graphene-boron nitride heterostructure, revealing multiple negative differential resistance peaks influenced by twist angle and phonon scattering, with implications for nano-electronic device design.

Contribution

It introduces a simulation of NDR in twisted graphene-boron nitride heterostructures, accounting for lattice mismatch and temperature effects, providing analytical expressions for resonant peaks.

Findings

Multiple NDR peaks depend on twist angle and bias voltage.

Lattice mismatch induces a unique NDR mechanism.

Temperature effects on PVR ratios are explained by electron-photon scattering.

Abstract

Two-dimensional (2D) crystals, such as graphene, hexagonal boron nitride and transitional metal dichalcogenides, have attracted tremendous amount of attention over the past decade due to their extraordinary thermal, electrical and optical properties, making them promising nano-materials for the next-generation electronic systems. A large number of heterostructures have been fabricated by stacking of various 2D materials to achieve different functionalities. In this work, we simulate the electron transport properties of a three-terminal multilayer heterostructure made from graphene nanoribbons vertically sandwiching a boron nitride tunneling barrier. To investigate the effects of the unavoidable misalignment in experiments, we introduce a tunable angular misorientation between 2D layers to the modeled system. Current-Voltage (I-V) characteristics of the device exhibit multiple NDR peaks originating from distinct mechanisms. A unique NDR mechanism arising from the lattice mismatch is captured and it depends on both the twisting angle and voltage bias. Analytical expressions for the positions of the resonant peaks observed in I-V characteristic are developed. To capture the slight degradation of PVR ratios observed in experiments when temperature increases from 2K to 300K, electron-photon scattering decoherence has been added to the simulation, indicating a good agreement with experiment works as well as a robust preservation of resonant tunneling feature.