Tunable metal-insulator transitions in bilayer graphene by thermal annealing

TL;DR

This study demonstrates that thermal annealing can reversibly induce and tune metal-insulator transitions in bilayer graphene, with potential applications in sensors due to environmental sensitivity.

Contribution

It reveals a controllable, reversible method to switch bilayer graphene between metallic and insulating states using thermal annealing and air exposure.

Findings

Metal-insulator transition occurs at 400 K annealing.

Transition temperature depends on annealing duration.

Reversible switching achieved by air exposure.

Abstract

Tunable and highly reproducible metal-insulator transitions have been observed in bilayer graphene upon thermal annealing at 400 K under high vacuum conditions. Before annealing, the sample is metallic in the whole temperature regime of study. Upon annealing, the conductivity changes from metallic to that of an insulator and the transition temperature is a function of annealing time. The pristine metallic state can be reinstated by exposing to air thereby inducing changes in the electronic properties by adsorbing water vapor, which makes graphene a technologically promising material for sensor applications.