Quasi one-dimensional van der Waals gold selenide with strong interchain interaction and giant magnetoresistance

An emerging quaternary semiconductor nanoribbon with gate-tunable anisotropic conductance

Two-dimensional noble transition metal chalcogenide (NTMC) semiconductors represent compelling building blocks for fabricating flexible electronic and optoelectronic devices. While binary and ternary compounds have been reported, the existence of quaternary NTMCs with a greater elemental degree of freedom remains largely unexplored. This study presents the pioneering experimental realization of a novel semiconducting quaternary NTMC material, AuPdNaS2, synthesized directly on Au foils through chemical vapor deposition. The ribbon-shaped morphology of the AuPdNaS2 crystal can be finely tuned to a thickness as low as 9.2 nm. Scanning transmission electron microscopy reveals the atomic arrangement, showcasing robust anisotropic features; thus, AuPdNaS2 exhibits distinct anisotropic phonon vibrations and electrical properties. The field-effect transistor constructed from AuPdNaS2 crystal demonstrates a pronounced anisotropic conductance (σmax/σmin = 3.20) under gate voltage control. This investigation significantly expands the repertoire of NTMC materials and underscores the potential applications of AuPdNaS2 in nano-electronic devices.

High Breakdown Current Density in Quasi-1D van der Waals Layered Material Ta2NiSe7

We synthesized ternary composition chalcogenide Ta2NiSe7, a quasi-one-dimensional (Q1D) material with excellent crystallinity. To utilize the excellent electrical conductivity property of Ta2NiSe7, the breakdown current density (JBD) according to thickness change through mechanical exfoliation was measured. It was confirmed that as the thickness decreased, the maximum breakdown voltage (VBD) increased, and at 18 nm thickness, 35 MA cm-2 of JBD was measured, which was 35 times higher than that of copper, which is commonly used as an interconnect material. By optimization of the exfoliation process, it is expected that through a theoretical model fitting, the JBD can be increased to about 356 MA cm-2. It is expected that the low-dimensional materials with ternary compositions proposed through this experiment can be used as candidates for current-carrying materials that are required for the miniaturization of various electronic devices.

Two-Dimensional Gold Halides: Novel Semiconductors with Giant Spin-Orbit Splitting and Tunable Optoelectronic Properties

We introduce a new family of 2D materials with unique structure and optoelectronic properties, namely, single-layer gold(I) halides (AuHals). We propose their stability as well as structural, electronic, and optical properties using first-principles calculations. The cleavage energy is found to be similar to that of graphene from graphite, indicating the possibility for mechanical exfoliation. We show that AuHals are stable and have tunable direct (AuBr) and indirect (AuI) band gaps depending on the number of layers. We discuss the possible origin of the giant spin-orbit coupling (SOC) induced conduction band splitting in terms of orbital-decomposed band structure to guide future investigations on the design of materials with highly effective SOC. Exceptionally high excitonic binding energy, high hole mobility, and tunable band gaps indicate that AuHals are promising candidates for optoelectronic devices with excellent performance.

Anisotropic Signal Processing with Trigonal Selenium Nanosheet Synaptic Transistors

Hardware implementation of an artificial neural network requires neuromorphic devices to process information with low energy consumption and high heterogeneity. Here we demonstrate an electrolyte-gated synaptic transistor (EGT) based on a trigonal selenium (t-Se) nanosheet. Due to the intrinsic low conductivity of the Se channel, the t-Se synaptic transistor exhibits ultralow energy consumption, less than 0.1 pJ per spike. More importantly, the intrinsic low symmetry of t-Se offers a strong anisotropy along its c- and a-axis in electrical conductance with a ratio of up to 8.6. The multiterminal EGT device exhibits an anisotropic response of filtering behavior to the same external stimulus, which enables it to mimic the heterogeneous signal transmission process of the axon-multisynapse biostructure in the human brain. The proof-of-concept device in this work represents an important step to develop neuromorphic electronics for processing complex signals.