One-dimensional van der Waals stacked p-type crystal Ta2Pt3Se8 for nanoscale electronics

Symmetry-Reduction Enhanced Polarization-Sensitive Photoresponse Based on One-Dimensional van der Waals Materials

Designing high-performance polarization-sensitive photodetectors is essential for photonic device applications. Anisotropic one-dimensional (1D) van der Waals (vdW) materials have provided a promising platform to that end. Despite significant advances in 1D vdW photonic devices, their performance is still far from delivering practical potential. Herein, we propose the design of high-performance polarization-sensitive photodetectors using unique 1D vdW materials. By leveraging the chemical vapor transport technique, we successfully fabricate high-quality 1D vdW Nb2Pd1-xSe5 (x = 0.29) nanowires. The 1D vdW Nb2Pd1-xSe5 photodetector exhibits a high mobility of ∼56 cm2/(V s) and superior photoresponse performance, including a high responsivity of 1A/W and an ultrafast response time of ∼8 μs under 638 nm illumination. Moreover, the 1D vdW Nb2Pd1-xSe5 photodetector demonstrates excellent polarization-sensitive photoresponse with a degree of linear polarization (DOLP) up to 0.85 and can be modulated by adjusting the gate voltage, laser power density, and wavelength. Those exceptional performance are believed to be relevant to the symmetry-reduction induced by the partial occupation of Pd sites. This study offers feasible approaches to enhance the anisotropy of 1D vdW materials and the modulation of their polarization-sensitive photoresponse, which may provide deep insights into the physical origin of anisotropic properties of 1D vdW materials.

One-Dimensional Atomic Chains for Ultimate-Scaled Electronics

The continuous downscaling of semiconducting channels in transistors has driven the development of modern electronics. However, with the component transistors becoming smaller and denser on a single chip, the continued downscaling progress has touched the physical limits. In this Perspective, we suggest that the emerging one-dimensional (1D) material system involving inorganic atomic chains (ACs) that are packed by van der Waals (vdW) interactions may tackle this issue. Stemming from their 1D crystal structures and naturally terminated surfaces, 1D ACs could potentially shrink transistors to atomic-scale diameters. Also, we argue that 1D ACs with few-atom widths allow us to revisit 1D materials and uncover physical properties distinct from conventional materials. These ultrathin 1D AC materials demand substantive attention. They may bring opportunities to develop ultimate-scaled AC-based electronic, optoelectronic, thermoelectric, spintronic, memory devices, etc.

Liquid Precursor-Assisted Chemical Vapor Deposition of One-Dimensional van der Waals Material Nb2Se9: Tunable Growth for Room-Temperature Gas Sensors

In this study, Nb₂Se₉, a one-dimensional (1D) material with van der Waals (vdWs) bonding, was synthesized by chemical vapor deposition (CVD). A liquid precursor was used to overcome the difficulty of controlling the length and density of Nb₂Se₉ by CVD due to the high melting point of Nb. Growth proceeded horizontally in a nano-ribbon shape on the substrate in the [100] direction, which had the most stable bonding distance, resulting in a preferred orientation of the (010) plane on the out-of-plane axis. Unlike that grown by conventional mechanical or chemical exfoliation, the nanoscale Nb₂Se₉ grown by CVD was uniform and did not have contaminants, such as dispersants, on its surface, meaning it could effectively induce reactions such as gas adsorption and desorption. It exhibited high sensitivity to NO₂ gas adsorption at room temperature (27 °C), and its behavior was confirmed in a high-humidity environment. For the first time, this study demonstrated the possibility of synthesizing a vdWs bonding-based 1D material by CVD, which is expected to be widely used in a variety of low-dimensional materials and devices.

Organic Dispersion of Mo3Se3- Single-Chain Atomic Crystals Using Surface Modification Methods

In this study, single-chain atomic crystals (SCACs), Mo₃Se₃^-, which can be uniformly dispersed, with an atomically thin diameter of ∼0.6 nm were modified to disperse in an organic solvent. Various surfactants were chosen to provide steric hindrance to aqueous-dispersed Mo₃Se₃^- by modifying the surface of Mo₃Se₃^-. The organic dispersions of surface-modified Mo₃Se₃^- SCACs in nonpolar solvent (toluene, benzene, and chloroform) were stable with a uniform diameter of 2 nm, and they have enhanced stability from oxidation (>10 days). With the surfactants that have a polystyrene tail group (PS-NH₂), the surface-modified Mo₃Se₃^- SCAC showed high compatibility with a polystyrene polymer matrix. Using the surface-modified Mo₃Se₃^- SCAC, a homogeneous Mo₃Se₃^-/polystyrene/toluene organogel was prepared. More importantly, the Mo₃Se₃^-/polystyrene organogel exhibits significantly enhanced mechanical properties, with the improvement of 202.27% and 279.52% for tensile strength and elongation, respectively, compared with that of the pure organogel. The surface-modified Mo₃Se₃^- had a similar structure with a polymer matrix, and the properties of the polymer can be improved even with a small addition of Mo₃Se₃^-.