Electrical noise inside the band gap of bilayer graphene

Abstract

Bilayer graphene (BLG), endowed with its electrostatically tunable band gap, plays a special role in next generation 2D materials based electronics. However, important aspects of its device characteristics are not fully understood, including in particular, the mechanism of electrical noise in its gapped state, which is essential to its operation. Here, we present the first systematic study of 1/f noise in conductance G in a dual-gated BLG as we tune the Fermi energy inside its large band gap. The normalized conductance noise initially increases dramatically by over an order of magnitude, which our analysis indicates, as arising due to percolative charge transport. When the Fermi energy reaches the charge neutrality point, we observe a remarkably constant irrespective of the magnitude of band gap, even though G decreases exponentially with band gap. We discuss that this is likely to be consequence of fluctuations in activated charge carriers far from the Fermi energy, enabled by charge traps of the substrate. Our results provide a coherent description of low frequency electrical noise in gapped BLG, paving the way for its implementation in the next-generation devices as well as representing benchmark for other gapped 2D materials.