Origin of electrical noise near charge neutrality in dual gated graphene device

TL;DR

This study explores low frequency 1/f noise in dual gated graphene devices, revealing how noise varies with gate voltages and charge inhomogeneity, and linking noise origins to charge and mobility fluctuations.

Contribution

It provides new insights into the dependence of electrical noise on gate voltages and charge inhomogeneity in dual gated graphene devices.

Findings

Noise increases with back gate density and peaks near charge inhomogeneity.

Noise is independent of top gate carrier density at low back gate densities.

Charge and mobility fluctuations are identified as sources of noise near charge neutrality.

Abstract

This letter investigates low frequency 1/ f noise in hBN encapsulated graphene device in a dual gated geometry. The noise study is performed as a function of top gate carrier density (nT G) at different back gate densities (nBG). The noise at low nBG is found to be independent of top gate carrier density. With increasing nBG, noise value increases and a noise peak is observed near charge inhomogeneity of the device. Further increase in nBG leads to decrease in noise magnitude. The shape of the noise is found to be closely related to charge inhomogeneity region of the device. Moreover, the noise and conductivity data near charge neutrality shows clear evidence of noise emanating from combination of charge number and mobility fluctuation