Direct observation of a gate tunable band-gap in electrical transport in ABC-trilayer graphene

TL;DR

This study provides the first direct electrical transport evidence of a gate-tunable energy gap in ABC-trilayer graphene, confirming theoretical predictions and highlighting its potential for tunable THz devices.

Contribution

It presents the first direct observation of an electric field tunable energy gap in ABC-trilayer graphene through transport measurements, validating theoretical models.

Findings

Energy gap observed via transport measurements confirms electric field tunability.

Temperature dependence indicates thermally activated transport over the gap.

Energy gap scales with electric field following a 3/2 power law.

Abstract

Few layer graphene systems such as Bernal stacked bilayer and rhombohedral (ABC-) stacked trilayer offer the unique possibility to open an electric field tunable energy gap. To date, this energy gap has been experimentally confirmed in optical spectroscopy. Here we report the first direct observation of the electric field tunable energy gap in electronic transport experiments on doubly gated suspended ABC-trilayer graphene. From a systematic study of the non-linearities in current \textit{versus} voltage characteristics and the temperature dependence of the conductivity we demonstrate that thermally activated transport over the energy-gap dominates the electrical response of these transistors. The estimated values for energy gap from the temperature dependence and from the current voltage characteristics follow the theoretically expected electric field dependence with critical exponent $3/2$. These experiments indicate that high quality few-layer graphene are suitable candidates for exploring novel tunable THz light sources and detectors.