Resonant tunnelling and negative differential conductance in graphene transistors

TL;DR

This paper demonstrates resonant tunnelling and negative differential conductance in graphene-based transistors with atomically thin boron nitride barriers, enabling ultra-fast, room-temperature electronic applications.

Contribution

It reports the first observation of resonant tunnelling of Dirac fermions through a boron nitride barrier in graphene transistors, showing gate-tunable negative differential conductance at room temperature.

Findings

Resonant tunnelling peak occurs when electronic spectra of electrodes align.

Negative differential conductance persists up to room temperature.

Device features ultra-thin barriers enabling fast carrier transit.

Abstract

The chemical stability of graphene and other free-standing two-dimensional crystals means that they can be stacked in different combinations to produce a new class of functional materials, designed for specific device applications. Here we report resonant tunnelling of Dirac fermions through a boron nitride barrier, a few atomic layers thick, sandwiched between two graphene electrodes. The resonant peak in the device characteristics occurs when the electronic spectra of the two electrodes are aligned. The resulting negative differential conductance persists up to room temperature and is gate voltage-tuneable due to graphene's unique Dirac-like spectrum. Whereas conventional resonant tunnelling devices comprising a quantum well sandwiched between two tunnel barriers are tens of nanometres thick, the tunnelling carriers in our devices cross only a few atomic layers, offering the prospect of ultra-fast transit times. This feature, combined with the multi-valued form of the device characteristics, has potential for applications in high-frequency and logic devices.