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

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