Influence of disorder on conductance in bilayer graphene under perpendicular electric field

TL;DR

This study experimentally investigates how disorder affects electron conductance in bilayer graphene under a perpendicular electric field, highlighting the importance of mobility for device performance.

Contribution

It provides experimental evidence linking disorder, conductance behavior, and mobility gaps in bilayer graphene under electric fields, with implications for FET applications.

Findings

Resistance increases steeply under high electric fields.

Conductance shows thermally activated and variable range hopping contributions.

Mobility gap aligns with theoretical band gap predictions.

Abstract

Electron transport in bilayer graphene placed under a perpendicular electric field is revealed experimentally. Steep increase of the resistance is observed under high electric field; however, the resistance does not diverge even at low temperatures. The observed temperature dependence of the conductance consists of two contributions: the thermally activated (TA) conduction and the variable range hopping (VRH) conduction. We find that for the measured electric field range (0 - 1.3 V/nm) the mobility gap extracted from the TA behavior agrees well with the theoretical prediction for the band gap opening in bilayer graphene, although the VRH conduction deteriorates the insulating state more seriously in bilayer graphene with smaller mobility. These results show that the improvement of the mobility is crucial for the successful operation of the bilayer graphene field effect transistor.