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Nanomechanical resonator devices are widely used as ultrasensitive mass detectors for fundamental studies and practical applications. The resonance frequency of the resonators shifts when a mass is loaded, which is used to estimate the mass. However, the shift signal is often blurred by the thermal noise, which interferes with accurate mass detection. Here, we demonstrate the reduction of the noise interference in mass detection in suspended graphene-based nanomechanical resonators, by using applied machine learning. Featurization is divided into image and sequential datasets, and those datasets are trained and classified using 2D and 1D convolutional neural networks (CNNs). The 2D CNN learning-based classification shows a performance with f1-score over 99% when the resonance frequency shift is more than 2.5% of the amplitude of the thermal noise range.

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The electrical properties of a single facet of an individual ZnO microwire were investigated. Electrode patterns with a Hall bar structure were deposited on the surface of the top facet of the ZnO microwire. Using a suspended and cross-linked poly­(methyl methacrylate) ribbon structure, it was possible to define the electrical connections only at the top surface, while avoiding those on the other five sides of the ZnO microwire. Current–voltage characteristics were examined, and Hall measurements were conducted with various magnetic fields. Through our device structure, the electrical properties could be directly probed at specific points on the ZnO surface in a reliable manner. The estimated electrical characteristics demonstrate that the carrier concentration and mobility of the ZnO surface varied along the axial direction of the wire. These results indicate that the charge carrier concentration on the surface of the micro-/nanowire can be sensitively changed according to the synthesis environment. In addition, it is worth noting that the nanoscale local Hall probes, fabricated by our technique, could probe the very slight variation of carrier concentration, which is difficult to detect by a standard transport measurement along the wire.

Weak interlayer couplings at 2D van der Waals (vdW) interfaces fundamentally distinguish out‐of‐plane charge flow, the information carrier in vdW‐assembled vertical electronic and optical devices, from the in‐plane band transport processes. Here, the out‐of‐plane charge transport behavior in 2D vdW semiconducting transition metal dichalcogenides (SCTMD) is reported. The measurements demonstrate that, in the high electric field regime, especially at low temperatures, either electron or hole carrier Fowler–Nordheim (FN) tunneling becomes the dominant quantum transport process in ultrathin SCTMDs, down to monolayers. For few‐layer SCTMDs, sequential layer‐by‐layer FN tunneling is observed to dominate the charge flow, thus serving as a material characterization probe for addressing the Fermi level positions and the layer numbers of the SCTMD films. Furthermore, it is shown that the physical confinement of the electron or hole carrier wave packets inside the sub‐nm thick semiconducting layers reduces the vertical quantum tunneling probability, leading to an enhanced effective mass of tunneling carriers.