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Mechanically exfoliated multilayer WS2 flakes are used as the channel of field effect transistors for low-power photodetection in the visible and near-infrared (NIR) spectral range. The electrical characterization as a function of the temperature reveals devices with n-type conduction and slightly different Schottky barriers at the drain and source contacts. The WS2 phototransistors can be operated in self-powered mode, yielding both a current and a voltage when exposed to light. The spectral photoresponse in the visible and the NIR ranges shows a high responsivity (4.5 μA/W) around 1250 nm, making the devices promising for telecommunication applications.

The Schottky barrier diode is a unipolar electronic device formed by the heterojunction of a metal and a semiconductor, widely used in various electronic and optoelectronic applications. Its rectifying current–voltage characteristic is typically derived using thermionic emission theory, which describes the transport of carriers over the Schottky barrier formed at the metal-semiconductor interface. In this paper, after briefly reviewing the metal-semiconductor heterojunction fundamentals and Landauer’s approach to electric transport, we propose an alternative way to derive the current–voltage behavior of a Schottky diode using Landauer’s formalism. This derivation can be directly applied to Schottky contacts between metals and low-dimensional materials, as demonstrated in the case of a 2D material. Additionally, we extend the proposed approach to account for tunneling currents through the barrier. Finally, we validate our findings with experimental data from a commercial Schottky diode, demonstrating excellent agreement. We also discuss non-ideal effects such as image-force lowering and lateral inhomogeneity of the Schottky barrier. This paper thus proposes an accessible and modern approach to understanding the Schottky diode current–voltage characteristics, making it suitable for both graduate- and postgraduate-level instruction.

We report the fabrication and optoelectronic characterization of field-effect transistors (FETs) based on few-layer ReSe2. The devices show n-type conduction due to the Cr contacts that form low Schottky barriers with the ReSe2 nanosheet. We show that the optoelectronic performance of these FETs is strongly affected by air pressure, and it undergoes a dramatic increase in conductivity when the pressure is lowered below the atmospheric one. Surface-adsorbed oxygen and water molecules are very effective in doping ReSe2; hence, FETs based on this two-dimensional (2D) semiconductor can be used as an effective air pressure gauge. Finally, we report negative photoconductivity in the ReSe2 channel that we attribute to a back-gate-dependent trapping of the photo-excited charges.

The Second Quantum Revolution refers to a contemporary wave of advancements and breakthroughs in the field of quantum physics that extends beyond the early developments of Quantum Mechanics that occurred in the 20th century. One crucial aspect of this revolution is the deeper exploration and practical application of quantum entanglement. Entanglement serves as a cornerstone in the ongoing revolution, contributing to quantum computing, communication, fundamental physics experiments, and advanced sensing technologies. Here, we present and discuss some of the recent applications of entanglement, exploring its philosophical implications and non-locality beyond Bell’s theorem, thereby critically examining the foundations of Quantum Mechanics. Additionally, we propose educational activities that introduce high school students to Quantum Mechanics by emphasizing entanglement as an essential concept to understand in order to become informed participants in the Second Quantum Revolution. Furthermore, we present the state-of-art developments of a largely unexplored and promising realization of real qubits, namely the molecular spin qubits. We review the available and suggested device architectures to host and use molecular spins. Moreover, we summarize the experimental findings on solid-state spin qubit devices based on magnetic molecules. Finally, we discuss how the Second Quantum Revolution might significantly transform law enforcement by offering specific examples and methodologies to address the evolving challenges in public safety and security.

We studied the temperature dependent transport properties and memory behaviour of ultrathin black phosphorus field-effect transistors. The devices show electrical conductance and field-effect mobility that decreases with the rising temperature. The field effect mobility, which depends also on the gate voltage sweep range, is 283 cm 2 V −1 s −1 at 150 K and reduces to 33 cm 2 V −1 s −1 at 340 K, when the voltage gate sweep range is ± 50 V. The transfer characteristics show a hysteresis width that increases with the temperature and is exploited to enable non-volatile memories with a wider programming window at higher temperatures.

We investigate the field emission properties of tetrapod-shaped zinc oxide (ZnO) micro and nanostructures prepared using a flame transport synthesis approach. Using a piezo-driven metallic tip as an anode, we performed a local characterization from the apex of a tetrapod arm, where the effective emitting area was limited below 1 μm 2 . This configuration allows extremely low turn-on voltages, of 7 V, and a field enhancement factor of 70 at an anode-cathode distance of 600 nm. The experimental data were analyzed using the Fowler–Nordheim model, evidencing a non-monotonous dependence of the turn-on field and the field enhancement factor on the cathode-anode separation distance in the range of 100–900 nm. The ZnO tetrapods demonstrated good current stability, highlighting their potential for high-performance, low-consumption electron-emitting devices with very low turn-on voltage.

We report the fabrication, electrical, and optical characterizations of few-layered black phosphorus (BP)-based field-effect transistor (FET). The fabricated device exhibits a p-type transport with hole mobility up to 175 cm 2  V −1  s −1 at V ds  = 1 mV. The transfer characteristics show a large hysteresis width that depends linearly on the gate voltage and decreases with the increasing drain bias. The fabricated device also ensures a non-volatile charge-trap memory behaviour, with a stable and long retention time. The material’s photodetection capabilities enhance the functionality of the device making it controllable by light. The photocurrent was observed to be linearly increasing with the light incident power and exposure time. As a photodetector, the transistor reaches a responsivity and detectivity up to 340 mA W −1 and 6.52 × 10 11 Jones under white light at 80  mW , respectively. Time-resolved measurements provide evidence of a long single exponential decay process through deep intra-gap states. Our results highlight the potential of a few layers BP as a nanomaterial for field-effect, memory, and optoelectronic devices. Graphical Abstract

We report the fabrication and optoelectronic characterization of field-effect transistors (FETs) based on few-layer ReSe . The devices show n-type conduction due to the Cr contacts that form low Schottky barriers with the ReSe nanosheet. We show that the optoelectronic performance of these FETs is strongly affected by air pressure, and it undergoes a dramatic increase in conductivity when the pressure is lowered below the atmospheric one. Surface-adsorbed oxygen and water molecules are very effective in doping ReSe ; hence, FETs based on this two-dimensional (2D) semiconductor can be used as an effective air pressure gauge. Finally, we report negative photoconductivity in the ReSe channel that we attribute to a back-gate-dependent trapping of the photo-excited charges.