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Ultrathin nanopore membranes based on 2D materials have demonstrated ultimate resolution toward DNA sequencing. Among them, molybdenum disulfide (MoS2) shows long-term stability as well as superior sensitivity enabling high throughput performance. The traditional method of fabricating nanopores with nanometer precision is based on the use of focused electron beams in transmission electron microscope (TEM). This nanopore fabrication process is time-consuming, expensive, not scalable, and hard to control below 1 nm. Here, we exploited the electrochemical activity of MoS2 and developed a convenient and scalable method to controllably make nanopores in single-layer MoS2 with subnanometer precision using electrochemical reaction (ECR). The electrochemical reaction on the surface of single-layer MoS2 is initiated at the location of defects or single atom vacancy, followed by the successive removals of individual atoms or unit cells from single-layer MoS2 lattice and finally formation of a nanopore. Step-like features in the ionic current through the growing nanopore provide direct feedback on the nanopore size inferred from a widely used conductance vs pore size model. Furthermore, DNA translocations can be detected in situ when as-fabricated MoS2 nanopores are used. The atomic resolution and accessibility of this approach paves the way for mass production of nanopores in 2D membranes for potential solid-state nanopore sequencing.

The growing importance of applications based on machine learning is driving the need to develop dedicated, energy-efficient electronic hardware. Compared with von-Neumann architectures, brain-inspired in-memory computing uses the same basic device structure for logic operations and data storage 1 – 3 , thus promising to reduce the energy cost of data-centric computing significantly 4 . While there is ample research focused on exploring new device architectures, the engineering of material platforms suitable for such device designs remains a challenge. Two-dimensional materials 5 , 6 such as semiconducting MoS2 could stand out as a promising candidate to face this obstacle thanks to their exceptional electrical and mechanical properties 7 – 9 . Here, we explore large-area grown MoS2 as an active channel material for developing logic-in-memory devices and circuits based on floating-gate field-effect transistors (FGFET). The conductance of our FGFETs can be precisely and continuously tuned, allowing us to use them as building blocks for reconfigurable logic circuits where logic operations can be directly performed using the memory elements. After demonstrating a programmable NOR gate, we show that this design can be simply extended to implement more complex programmable logic and functionally complete sets of functions. Our findings highlight the potential of atomically thin semiconductors for the development of next-generation low-power electronics.

Super-resolution microscopy opened diverse novel research directions by overcoming the classical resolution limit. Revealing structures beyond the diffraction limit was made possible by exploiting the fluorescent emission of individual fluorophores. Involving sample properties to apply these techniques entails a redefinition of the resolution parameter. Here, we propose a new method for assessing the resolution of individual super-resolved images based on image partial phase auto-correlation. The novel algorithm is model-free and does not require any user-defined parameters. We demonstrate its performance on a wide variety of imaging modalities, including diffraction-limited techniques. Finally, we show how our method can be used to optimize image acquisition and post-processing in superresolution microscopy.

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Point defects can have significant impacts on the mechanical, electronic and optical properties of materials. The development of robust, multidimensional, high-throughput and large-scale characterization techniques of defects is thus crucial, from the establishment of integrated nanophotonic technologies to material growth optimization. Here, we demonstrate the potential of wide-field spectral single-molecule localization microscopy (spectral SMLM) for the determination of ensemble spectral properties, as well as characterization of spatial, spectral and temporal dynamics of single defects in CVD-grown and irradiated exfoliated hexagonal boron-nitride (hBN) materials. We characterize the heterogeneous spectral response of our samples, and identify at least two types of defects in CVD-grown materials, while irradiated exfoliated flakes show predominantly only one type of defect. We analyze the blinking kinetics and spectral emission for each type of defects, and discuss their implications with respect to the observed spectral heterogeneity of our samples. Our study shows the potential of widefield spectral SMLM techniques in material science and paves the way towards quantitative multidimensional mapping of defect properties.

Classical nanopore sensing relies on the measurement of the ion current passing through a nanopore. Whenever a molecule electrophoretically translocates through the narrow constriction, it modulates the ion current. Although this approach allows one to measure single molecules, the access resistance limits the spatial resolution. This physical limitation could potentially be overcome by an alternative sensing scheme taking advantage of the current across the membrane material itself. Such an electronic readout would also allow better temporal resolution than the ionic current. In this work, we present the fabrication of an electrically contacted molybdenum disulfide (MoS2) nanoribbon integrated with a nanopore. DNA molecules are sensed by correlated signals from the ionic current through the nanopore and the transverse current through the nanoribbon. The resulting signal suggests a field-effect sensing scheme where the charge of the molecule is directly sensed by the nanoribbon. We discuss different sensing schemes such as local potential sensing and direct charge sensing. Furthermore, we show that the fabrication of freestanding MoS2 ribbons with metal contacts is reliable and discuss the challenges that arise in the fabrication and usage of these devices.

Point defects significantly influence the optical and electrical properties of solid-state materials due to their interactions with charge carriers, which reduce the band-to-band optical transition energy. There has been a demand for developing direct optical imaging methods that would allow in situ characterization of individual defects with nanometer resolution. Here, we demonstrate the localization and quantitative counting of individual optically active defects in monolayer hexagonal boron nitride using single molecule localization microscopy. By exploiting the blinking behavior of defect emitters to temporally isolate multiple emitters within one diffraction limited region, we could resolve two defect emitters with a point-to-point distance down to ten nanometers. The results and conclusion presented in this work add unprecedented dimensions toward future applications of defects in quantum information processing and biological imaging.