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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.

We report on the current-carrying capacity of the nanowires made from the quasi-1D van der Waals metal tantalum triselenide capped with quasi-2D boron nitride. The chemical vapor transport method followed by chemical and mechanical exfoliation were used to fabricate the mm-long TaSe3 wires with the lateral dimensions in the 20 to 70 nm range. Electrical measurements establish that the TaSe3/h-BN nanowire heterostructures have a breakdown current density exceeding 10 MA cm(-2)-an order-of-magnitude higher than that for copper. Some devices exhibited an intriguing step-like breakdown, which can be explained by the atomic thread bundle structure of the nanowires. The quasi-1D single crystal nature of TaSe3 results in a low surface roughness and in the absence of the grain boundaries. These features can potentially enable the downscaling of the nanowires to lateral dimensions in a few-nm range. Our results suggest that quasi-1D van der Waals metals have potential for applications in the ultimately downscaled local interconnects.