Influence of Disorder on Conductance in Bilayer Graphene under Perpendicular Electric Field

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.

Electron-state engineering of bilayer graphene by ionic molecules

“…29 It should be noted that the K and K 0 points (Dirac points) are folded into the C point in the graphene with 6 Â 6 lateral periodicity. The gap value is comparable to those obtained in bilayer graphene under extremely high external electric field [9][10][11] or that with doped molecules. [12][13][14][15] In this structure, the top of the valence band and the bottom of the conduction band possess their p-state nature and are localized on the bilayer graphene.…”

“…According to this potential energy difference, the sandwiched bilayer graphene has a finite energy gap around the Dirac point due to the band shift and repulsion between two pairs of linear dispersion bands, as in the case of bilayer graphene under an external electric field. [9][10][11] Dividing the potential difference by the interlayer spacing, the effective electric field applied on bilayer graphene is found to be 2.24 V/nm. Therefore, the fundamental energy gap and electronic structure of bilayer graphene can be controlled by tuning the cation-anion pair that causes the characteristic strength of the local electric field across the sandwiched bilayer graphene.…”

The electronic properties of bilayer graphene

“…Since then, the majority of experiments probing the band gap have used single or dual gate devices based on exfoliated bilayer graphene flakes [19,20]. The band gap has now been observed in a number of different experiments including photoemission [16], magnetotransport [20], infrared spectroscopy [55, 78-80, 129, 130], electronic compressibility [131,132], scanning tunnelling spectroscopy [133], and transport [19,31,[134][135][136][137][138][139].…”

Gate-controlled conductance through bilayer graphene ribbons

“…The improvement in bilayer graphene fabrication could make possible the obtention of similar electronic and optical gaps in these systems. 11,15,16 Monolayer graphene nanoribbons (MGNs) stand out as optimal electrodes for systems based on bilayer graphene, with the aim of achieving the best integration of nanoelectronic components. Narrow monolayer graphene nanoribbons have recently been obtained by different methods, [17][18][19] and the observation of an electrically induced gap in bilayer graphene nanoribbons (BGNs) has been recently reported.…”