Highlights What are the main findings? Grazing-incidence SEM strongly enhances surface-sensitive contrast in ultrathin MoS2 coatings. Sobel-based edge analysis quantitatively confirms increased morphological information content. MoS2 colloids predominantly contain mono- and few-layer nanosheets after settling. What are the implications of the main findings? Simple stage tilting enables surface-sensitive SEM without hardware modification. Method provides reliable morphological assessment of ultrathin 2D coatings. Approach is applicable to other layered coatings and nanostructured films.Highlights What are the main findings? Grazing-incidence SEM strongly enhances surface-sensitive contrast in ultrathin MoS2 coatings. Sobel-based edge analysis quantitatively confirms increased morphological information content. MoS2 colloids predominantly contain mono- and few-layer nanosheets after settling. What are the implications of the main findings? Simple stage tilting enables surface-sensitive SEM without hardware modification. Method provides reliable morphological assessment of ultrathin 2D coatings. Approach is applicable to other layered coatings and nanostructured films.Abstract Ultrathin two-dimensional (2D) coatings exhibit functional properties that are strongly defined by morphological features such as sheet edges, fracture sites, overlaps, folds, and local thickness variations, which are often difficult to resolve using conventional scanning electron microscopy (SEM) configurations. Here, we introduce a grazing-incidence SEM approach based on controlled sample tilting close to 90 degrees for enhancing surface sensitivity and morphological feature detectability in ultrathin coatings. The method is proved on colloidal MoS2 nanosheet coatings prepared by liquid-phase exfoliation. Optical absorption spectroscopy confirms the presence of mono- and few-layer MoS2 nanosheets in the dispersion, confirming the ultrathin nature of the deposited coating. Compared to standard 0 degrees imaging, grazing-incidence SEM reveals clearer boundaries and discontinuities. Quantitative Sobel-based image analysis supports these observations, showing an increase in edge density from 5.9% to 7.6% and in average gradient magnitude from 0.151 to 0.172 a.u. under grazing incidence, indicating a higher amount of retrievable morphological information. The proposed approach relies only on standard stage tilting and provides a broadly applicable framework for the surface-sensitive morphological characterization of ultrathin 2D coatings and thin films.

The integration of logic, memory, and neuromorphic functions within a single electronic platform is a central goal for next‐generation information technologies. Two‐dimensional (2D) materials, with their atomic thickness and tunable electronic properties, offer an ideal foundation for multifunctional device architectures. However, realizing complementary operation in 2D electronics remains challenging due to the scarcity of stable p‐type semiconductors and the difficulty of controlling interfacial charge transfer. Here, we demonstrate interface‐engineered complementary field‐effect transistors (cFETs) based on molybdenum diselenide (MoSe2) and MoSe2/chromium oxychloride (CrOCl), enabling tunable n‐ and p‐type conduction via van der Waals interfacial coupling. Pristine MoSe2 exhibits n‐type transport with an electron mobility of approximately 18 cm2 V−1 s−1, while charge transfer from CrOCl induces robust p‐type conduction with a hole mobility of about 1.1 cm2 V−1 s−1, allowing the realization of balanced resistive‐load and CMOS inverter circuits with noise margins up to 40% of the supply voltage. Compared with conventional 2D FETs, this approach achieves simultaneous logic, nonvolatile memory, and synaptic functionalities within a single device, demonstrating multilevel data storage and long‐term synaptic plasticity. These results reveal that interface coupling in MoSe2/CrOCl heterostructures enables precise polarity control without chemical doping, overcoming a key limitation of 2D electronics. Overall, this work establishes MoSe2/CrOCl cFETs as a versatile platform bridging digital logic, memory, and neuromorphic computing within all‐2D architectures.

The 2-D transition metal dichalcogenides (TMDs) have emerged as promising materials for next-generation optoelectronic devices. Nevertheless, their application in self-powered photodetectors remains challenging, as device performance is often constrained by high dark currents and inefficient charge separation at zero bias. In this work, we demonstrate a self-powered photodetector based on a tungsten diselenide on chromium oxychloride (WSe2/CrOCl) van der Waals heterostructure with Schottky contacts. Electrical and optoelectronic characterizations reveal that the chromium oxychloride (CrOCl) substrate acts not only as a high-quality dielectric that drastically suppresses the dark current, but also as an active channel modulator. Leveraging its exceptionally high work function, CrOCl induces a massive interfacial charge transfer that p-dopes the WSe2 layer. Under illumination, this synergistic interlayer coupling overcomes contact barrier restrictions, amplifying the local built-in electric field at the Schottky junction and maximizing the spontaneous extraction of photogenerated carriers. Overall, this work demonstrates that integrating WSe2 with CrOCl provides a highly effective strategy to significantly enhance the performance of self-powered photodetectors.

The growing need for efficient processing of large amounts of data in compact electronic systems is driving interest in investigating alternative device architectures. 2D material-based devices exhibiting anti-ambipolar behaviour represent a promising option to address this need. In this work, we investigate a WSe2-based field-effect transistor that shows ambipolar conduction with dominant n-type behaviour in the dark. Under illumination, using either diffuse white LED light or a collimated red laser, the device exhibits a transition to anti-ambipolar transport, with a prominent current peak in a narrow driving voltage range, which is desirable for fast switching logic applications. This response allows for the identification, under controlled illumination conditions, of three distinct current levels in three different bias regions, which are suitable for implementing a three-state logic device. The peak amplitude varies linearly with light intensity, and the corresponding photodetection performance results in a significant responsivity of 0.13 A W-1 under red laser illumination. The light-induced transition from ambipolar to anti-ambipolar behaviour is qualitatively described through energy band diagrams, with the photocurrent peak corresponding to the n-p transition point observed in the dark.

This report is on the field emission properties of WSe 2 nanoflowers synthesized via a solution‐phase colloidal approach, uniformly deposited on Si/SiO 2 substrates. Structural and spectroscopic data confirm the formation of highly crystalline nanoflowers with predominantly 1T′ phase content and minimal surface oxidation. Field emission measurements, performed in vacuum using a nanomanipulated tungsten probe, reveal a low turn‐on voltage and a field enhancement factor ranging from ≈70 at cathode‐anode separation distance of 100 nm, to ≈10 for distance increased to 900 nm, as resulting by the analysis in the framework of the Fowler–Nordheim model. WSe 2 nanoflowers offer competitive performance combined with excellent stability, attributable to their hierarchical architecture and metallic character. These results demonstrate the potential of WSe 2 nanoflowers as efficient cold cathode materials for next‐generation vacuum electronic applications.

ABSTRACT Suspended indium arsenide (InAs) nanowires offer a unique platform for studying surface‐driven transport phenomena due to their high surface‐to‐volume ratio and the absence of dielectric interfaces. In this work, we investigate the role of surface states in InAs nanowire field‐effect transistors. Electrical characterization reveals a high electron mobility of ≈1500 cm2V−1s−1, alongside a subthreshold swing of 1.49 V dec−1, indicating a reduced gate efficiency caused by surface traps. Temperature‐dependent analysis yields activation energies of ∼100 meV, confirming the dominant influence of shallow trap states on both threshold voltage and subthreshold slope. Under pulsed optical excitation, the devices exhibit persistent negative photoconductivity and gate‐tunable hysteresis. The on/off current ratio exceeds 105 at 200 K. These effects are attributed to a photogating mechanism controlled by the interplay between gate voltage and photoinduced trap occupation. The demonstrated ability to modulate long and short‐term memory behavior through optical and electrical stimuli highlights the potential of these nanowire devices for neuromorphic applications.

We report the fabrication and characterization of flexible cold cathodes based on graphite nanoplatelet (GNP) coatings on silicone rubber substrates. GNPs, synthesized via thermal exfoliation of graphite bisulfate and sonication in acetone, form nanostructured coatings with controlled roughness and thickness. Morphological, structural, and spectroscopic analyses confirm the presence of crystalline, few-layer graphitic domains. Field emission was locally probed by using a nanomanipulated tungsten tip anode inside a scanning electron microscope, revealing a turn-on voltage as low as 8.2 V and a field enhancement factor of similar to 80 at an anode-cathode distance of 100 nm. Emission characteristics are measured in different substrate curvature configurations: sharper bending alters the exposure of nanoplatelet edges, influencing the turn-on voltage and the field enhancement factor. The emitters exhibit excellent stability, robustness under strain, and thermally activated conduction behaviour with an activation energy of similar to 0.31 eV. Our findings demonstrate that GNP-coated silicone rubbers are a scalable, low-cost, and mechanically adaptive platform for next-generation vacuum microelectronics, enabling flexible, high-performance electron sources with nanoscale control and real-time tunability.

Semiconductive nanotubes offer the potential for miniaturized transistors with enhanced gate control through various configurations. In this work, we fabricated and electrically characterized a single WS2 nanotube-based field-effect transistor under both dark and white light illumination at ambient pressure and temperature. At drain voltages higher than 1 V, the device exhibits ambipolar conduction, with a hole mobility of 0.2 cm(2) V-1 s(-1) and an electron mobility of 0.13 cm(2) V-1 s(-1) at V-ds = 2 V. The gate modulation has been extensively investigated, applying gate voltages up to 100 V. Furthermore, the WS2 nanotube-based device was evaluated as a photodetector, demonstrating light-induced modulation of the channel current via both gate and drain control. The single WS2 nanotube-based transistor also operates in self-powered mode, achieving a short-circuit current of 2.6 pA and an open-circuit voltage of approximately 3 mV. The electrical properties of this device show potential for complementary metal-oxide semiconductor (CMOS) applications, and contribute to the development of optoelectronic devices, including self-powered photodetectors.

van der Waals heterostructures between two-dimensional (2D) materials offer versatile platforms for innovative electrical device architectures and applications. Black phosphorus (BP) and molybdenum disulfide (MoS2) emerge as promising candidates for heterostructures, owing to their exceptional electronic properties and gate-tunable capabilities. In this work, we study the electrical properties of a vertical BP/MoS2 heterostructure fabricated onto a SiO2/Si substrate in a back-gate configuration. We focus on the effect of air pressure, from atmospheric pressure to 10-4 mbar, and show that best electrical performances are enabled at the lower pressure. The heterostructure exhibits gate-tunable rectifying current-voltage characteristics, with a rectification ratio close to 103. The rectifying characteristics present a kink in the forward region revealing different conduction mechanisms, namely drift-diffusion and band-to-band tunneling. Furthermore, when used as a transistor, the device shows n-type conduction, high gate modulation with ON/OFF ratio of 10 6 , low off-state current of 10 - 14 A and mobility of 1.6 cm2 V-1 s-1. The results of this work highlight the potential of BP/MoS2 heterostructures for applications in low-power electronics, high-performance transistors, and sensitive pressure sensors.

This report is on the field emission properties of WSe2 nanoflowers synthesized via a solution-phase colloidal approach, uniformly deposited on Si/SiO2 substrates. Structural and spectroscopic data confirm the formation of highly crystalline nanoflowers with predominantly 1T ' phase content and minimal surface oxidation. Field emission measurements, performed in vacuum using a nanomanipulated tungsten probe, reveal a low turn-on voltage and a field enhancement factor ranging from approximate to 70 at cathode-anode separation distance of 100 nm, to approximate to 10 for distance increased to 900 nm, as resulting by the analysis in the framework of the Fowler-Nordheim model. WSe2 nanoflowers offer competitive performance combined with excellent stability, attributable to their hierarchical architecture and metallic character. These results demonstrate the potential of WSe2 nanoflowers as efficient cold cathode materials for next-generation vacuum electronic applications.

In this study, we present a hybrid optoelectronic device consisting of tungsten disulfide nanotubes (NTs) deposited on graphene electrodes, forming ohmic contacts that enable efficient charge transport. The heterostructure is fabricated on a flexible polyethylene terephthalate substrate. Comprehensive electrical and optoelectronic characterizations are conducted under various environmental conditions, with a focus on photocurrent response and the photovoltaic effect. The device shows a broadband photoresponse from 405 to 900 nm, reaching its best performance at 880 nm, where it delivers a peak responsivity of 0.07 mA W-1, a specific detectivity of 2.3 × 107Jones and rise/decay constants of 1.6 s/1.5 s, measured under 405 nm illumination at an incident power of 0.19 mW. A long-time tail of 23 s is also observed, attributed to trap-assisted processes. The long-wavelength cut-off (∼ 880 nm) corresponds to an indirect bandgap of 1.4 ± 0.1 eV for the NTs. Under 520 nm illumination, the heterostructure generates an open circuit photovoltage of ∼15 mV and a short-circuit photocurrent of ∼0.08 nA, confirming the presence of a photovoltaic effect. Illumination at 405 nm reveals a photocurrent response that is sensitive to changes in environmental pressure. These results highlight the multifunctionality of the heterostructure, which can be optimized for photovoltaic conversion, wearable photodetectors, and sensing applications.

Lignin, a by-product of the pulp and paper industry and biomass processing, features a chemical structure rich in aromatic rings and functional groups such as ethers, alcohols, phenols and carboxyls, as well as electrical properties that can make it a promising material for various uses in a waste-to-application approach. This study investigates the composition, morphology, and DC electrical behavior of three distinct lignins: two derived from the Kraft extraction process and differing in their post-treatment ( L 1, L 2) and one ( L 3) extracted from Cynara cardunculus using an ethanolic organosolv process catalyzed by aqueous ammonia. Morphological analyses reveal that L 3 exhibits features intermediate between the smooth structure of L 1 and the fibrillar nanostructure of L 2. When used as the active layer in interdigitated devices, their I – V characteristics on a semilogarithmic plot exhibit butterfly-shaped curves, showing strong dependence on temperature and pressure. L 1 and L 3 are similar, while L 2 differs substantially, reflecting variations in functional group density and morphology. The low electrical conductivity, the dependence on morphology, and the hysteretic electrical behavior suggest that ionic conduction plays a significant role in the overall charge transport, with conductivity scaling as L 2 > L 3 > L 1 and increasing with pressure and temperature. Morphology-dependent adsorption of air molecules primarily enhances ionic conduction, and the good fit to the Arrhenius model suggests that charge transport occurs via carrier hopping across localized energy barriers. This study highlights the diverse electrical properties achievable with lignins with different extraction histories and their tunability through processing methods, enabling tailoring to specific applications and making lignin a versatile and sustainable material for electronic devices.

Scanning electron microscopy (SEM) is a powerful tool for the morphological characterization of multiscale nanomaterials, including two-dimensional (2D) systems such as graphene and molybdenum disulfide (MoS₂). However, conventional SEM imaging often struggles to resolve nanoscale features due to limited contrast and depth sensitivity, especially when dealing with ultrathin layers. In this work, we propose and demonstrate a simple yet effective strategy to overcome these limitations by exploiting grazing-incidence (radent) observation, achieved through a controlled tilting of the sample close to 90°. This approach significantly enhances the emission of secondary electrons from near-surface regions, thereby increasing image contrast and revealing morphological details, such as edges, ripples, defects, and overlapping layers, that remain hidden under standard imaging conditions. Optical characterization of the prepared MoS₂ colloids further supports the formation of monolayer and few-layer sheets, validating the structural information obtained from SEM. Interestingly, this approach recalls natural strategies observed in living organisms, where grazing-angle vision improves edge perception and surface recognition and therefore it can be considered as bio-inspired. Beyond its use with MoS₂, this biomimetic methodology offers a versatile and broadly applicable solution for improving morphological analysis of 2D nanomaterials and thin films, providing deeper insights into their structural characterization.

The search for promising and sustainable materials for advanced electronic applications has recently drawn attention to lignin. As a major by-product of pulping processes, lignin features a complex aromatic structure, rich in aliphatic and aromatic ethers, as well as hydroxyl and carboxyl functional groups, which endow it with unique chemical and electronic properties. In this study, we present a comparative analysis of three distinct lignins. Two of them (L1 and L2) are derived from the Kraft pulping process, while the third (L3) is extracted from Cynara cardunculus using an ethanolic organosolv method. These lignins are investigated as active layers in an interdigitated electronic device. To explore in depth the influence of the compositional, structural, morphological and chemical properties of the three lignins on dielectric relaxation dynamics and charge transport mechanisms, several advanced analytical techniques were adopted, including Electrochemical Impedance Spectroscopy (EIS), Nyquist Plots (NP), Broadband Dielectric Spectroscopy (BDS), and Complex Power (CP) representations. Our consistent workflow included the same interdigitated electrode (IDE) platform, identical frequency window, a unified BDS formalism, and a common base EIS circuit design tailored to the observed Nyquist Plot features. Our findings revealed that the extraction process enables tuning of the lignin properties. Whilst L1 exhibited smooth, compact morphology and a higher polymerization degree, limiting charge mobility and resulting in inferior electrical and capacitive performance, L2 featured a fibrous structure with higher content in carboxyl groups and ashes, which significantly enhanced the conductivity and capacitance. L3 displayed an intermediate morphology with a high concentration of aliphatic hydroxyl groups, offering a balanced blend of chemical and structural properties. In this work, we reveal the potential of lignin as a versatile dielectric material exhibiting supercapacitive behavior among other properties.

We report the fabrication and characterization of suspended InAs nanowire field-effect transistors (FETs) for optoelectronic memory applications. The devices were realized by depositing InAs nanowires onto a polymethyl methacrylate (PMMA) sacrificial layer, followed by metal contact definition and PMMA removal to achieve a fully suspended architecture. Electrical measurements under high vacuum revealed n-type transistor behavior with good gate modulation and Ohmic contacts. Under laser illumination, the devices exhibited both positive and negative photoconductivity, depending on the gate bias, due to the interaction between photogenerated carriers and surface trap states. By exploiting the hysteretic transfer characteristics and the optical response, we demonstrated memory operation controlled by two independent variables: gate voltage and illumination condition. The device showed well-separated and stable current levels corresponding to different write–read–erase states, highlighting its potential as a multifunctional optoelectronic memory for future nanoelectronic circuits.

Owing to their large size and flexibility, 2D nanostructures (e.g., graphene, graphene oxide, single-layer molybdenum disulfide, etc.) are technologically exploited in a supported form. Glass, silicon, and polymers are typical substrates. In the characterization of these 2D nanostructures, important morphological information (e.g., size, shape factor, presence of defects, etc.) can be obtained through an investigation based on scanning electron microscopy (SEM). However, the observation of these extremely thin 2D nanostructures is characterized by poor contrast, and therefore, all morphological features are not clearly visible in SEM micrographs. Herein, it is shown that under a high sample tilting condition, SEM observations are also capable of providing images with very good contrast. Such high sample tilting can be obtained by positioning the sample vertically and then conveniently reducing this angle (90°) by tilting the sample up to achieve a well-focused image.

Recent interest in flexible sensors, fueled by their affordability, wearability, lightweight design, and ease of fabrication, has driven advancements in applications and fundamental understanding. Herein, we explore the synthesis route of the three-dimensional (3D) graphene-coated sponges and investigate their mechanical and electronic transport properties. Tensile and compression tests on the graphene coated sponges demonstrate Young's modulus of around 0.075 MPa. Electrical measurements with ohmic contacts show DC conductivity as low as 0.5 S/cm. Bonding durability and wettability tests under water immersion and ultrasonic agitation confirmed the strong adhesion and enhanced hydrophobicity of the graphene coating, demonstrating its mechanical and chemical robustness. Temperature measurements reveal a non-monotonic behavior in the sponge's resistance as the temperature decreases. The resistance exhibits a pronounced peak around 250 K as the temperature drops from 295 K to 200 K, followed by a steady increase from 200 K to 77 K. Field emission measurements show a stable current and a reduction in turn-on voltage as the spacing between the anode and the emitting surface decreases, revealing a low turn-on voltage of about 13 V and a field enhancement factor of 286 at an anode-cathode distance of 300 nm. Experimental data are analyzed using the Fowler-Nordheim model, evidencing a non-monotonic dependence of the field enhancement factor on the cathode-anode separation distance in the range of 100-500 nm. The results show that such a flexible 3D graphene coated sponge can be utilized as a sensitive thermistor, a field emitter, and a pressure sensor.