Nature of the 1/ f noise in graphene-direct evidence for the mobility fluctuation mechanism.

The nature of the low-frequency 1/ f noise in electronic materials and devices is one of the oldest unsolved physical problems ( f is the frequency). The fundamental question of the noise source-fluctuations in the mobility vs . number of charge carriers-is still debated. While there are several pieces of evidence to prove that the 1/ f noise in semiconductors is due to the fluctuations in the number of the charge carriers, there is no direct evidence of the mobility fluctuations as the source of 1/ f noise in any material. Herein, we measured noise in an h -BN encapsulated graphene transistor under the conditions of geometrical magnetoresistance to directly assess the mechanism of low-frequency electronic current fluctuations. It was found that the relative noise spectral density of the graphene resistance fluctuations depends non-monotonically on the magnetic field ( B ) with a minimum at approximately μ 0 B ≅ 1 ( μ 0 is the electron mobility). This observation proves unambiguously that mobility fluctuations are the dominant mechanism of electronic noise in high-quality graphene. Our results are important for all proposed applications of graphene in electronics and add to the fundamental understanding of the 1/ f noise origin in any electronic device.