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Superconducting-based electronic devices have shown great potential for future quantum computing applications. One key building block device is a superconducting field-effect transistor based on a superconductor–semiconductor–superconductor Josephson-junction (JJ) with a gate-tunable semiconducting channel. However, the performance of such devices is highly dependent on the quality of the superconductor to semiconductor interface. In this study, we present an alternative method to obtain a high-quality interface by using intimate contact. We investigate the proximity-induced superconductivity in chiral crystal tellurium (Te) and fabricate a PdxTe–Te–PdxTe JJ with an ambipolar supercurrent that is gate-tunable and exhibits multiple Andreev reflections. The semiconducting two-dimensional Te single crystal is grown hydrothermally and partially converted to superconducting PdxTe by controlled annealing. Our work demonstrates a promising path for realizing controllable superconducting electronic devices with high-quality superconducting interfaces; thus, we can continue to advance the field of quantum computing and other interface-based technologies.

A material with reversible temperature change capability under an external electric field, known as the electrocaloric effect (ECE), has long been considered as a promising solid-state cooling solution. However, electrocaloric (EC) performance of EC materials generally is not sufficiently high for real cooling applications. As a result, exploring EC materials with high performance is of great interest and importance. Here, we report on the ECE of ferroelectric materials with van der Waals layered structure (CuInP2S6or CIPS in this work in particular). Over 60% polarization charge change is observed within a temperature change of only 10 K at Curie temperature. Large adiabatic temperature change (|ΔT|) of 3.3 K and isothermal entropy change (|ΔS|) of 5.8 J kg–1K–1at |ΔE| = 142.0 kV cm–1and at 315 K (above and near room temperature) are achieved, with a large EC strength (|ΔT|/|ΔE|) of 29.5 mK cm kV–1. The ECE of CIPS is also investigated theoretically by numerical simulation, and a further EC performance projection is provided.

We demonstrate room-temperature ferroelectric field-effect transistors (Fe-FETs) with MoS2and CuInP2S6two-dimensional (2D) van der Waals heterostructure. The ferroelectric CuInP2S6is a 2D ferroelectric insulator, integrated on top of MoS2channel providing a 2D/2D semiconductor/insulator interface without dangling bonds. The MoS2- and CuInP2S6-based 2D van der Waals heterostructure Fe-FETs exhibit a clear counterclockwise hysteresis loop in transfer characteristics, demonstrating their ferroelectric properties. This stable nonvolatile memory property can also be modulated by the back-gate bias of the MoS2transistors because of the tuning of capacitance matching between the MoS2channel and the ferroelectric CuInP2S6, leading to the enhancement of the on/off current ratio. Meanwhile, the CuInP2S6thin film also shows resistive switching characteristics with more than four orders of on/off ratio between low- and high-resistance states, which is also promising for resistive random-access memory applications.

We have determined the spin–orbit scattering length of two-dimensional layered 2H-TaSe2metallic crystals by detailed characterization of the weak antilocalization phenomena in this strong spin–orbit interaction material. By fitting the observed magneto-conductivity, the spin–orbit scattering length for 2H-TaSe2is determined to be 17 nm in the few-layer films. This small spin–orbit scattering length is comparable to that of Pt, which is widely used to study the spin Hall effect, and indicates the potential of TaSe2for use in spin Hall effect devices. A material must also support large charge currents in addition to strong spin–orbit coupling to achieve spin-transfer-torque viathe spin Hall effect. Therefore, we have characterized the room temperature breakdown current density of TaSe2in air, where the best breakdown current density reaches 3.7 × 107A/cm2. This large breakdown current further indicates the potential of TaSe2for use in spin-torque devices and two-dimensional device interconnect applications.

Phosphorene, a elemental 2D material, which is the monolayer of black phosphorus, has been mechanically exfoliated recently. In its bulk form, black phosphorus shows high carrier mobility (∼10 000 cm2/V·s) and a ∼0.3 eV direct band gap. Well-behaved p-type field-effect transistors with mobilities of up to 1000 cm2/V·s, as well as phototransistors, have been demonstrated on few-layer black phosphorus, showing its promise for electronics and optoelectronics applications due to its high hole mobility and thickness-dependent direct band gap. However, p–n junctions, the basic building blocks of modern electronic and optoelectronic devices, have not yet been realized based on black phosphorus. In this paper, we demonstrate a gate-tunable p–n diode based on a p-type black phosphorus/n-type monolayer MoS2van der Waals p–n heterojunction. Upon illumination, these ultrathin p–n diodes show a maximum photodetection responsivity of 418 mA/W at the wavelength of 633 nm and photovoltaic energy conversion with an external quantum efficiency of 0.3%. These p–n diodes show promise for broad-band photodetection and solar energy harvesting.

In this article, we study the properties of metal contacts to single-layer molybdenum disulfide (MoS2) crystals, revealing the nature of switching mechanism in MoS2transistors. On investigating transistor behavior as contact length changes, we find that the contact resistivity for metal/MoS2junctions is defined by contact area instead of contact width. The minimum gate dependent transfer length is ∼0.63 μm in the on-state for metal (Ti) contacted single-layer MoS2. These results reveal that MoS2transistors are Schottky barrier transistors, where the on/off states are switched by the tuning of the Schottky barriers at contacts. The effective barrier heights for source and drain barriers are primarily controlled by gate and drain biases, respectively. We discuss the drain induced barrier narrowing effect for short channel devices, which may reduce the influence of large contact resistance for MoS2Schottky barrier transistors at the channel length scaling limit.