Investigating thermal properties of 2D non-layered material using a NEMS-based 2-DOF approach towards ultrahigh-performance bolometer.

Two-dimensional (2D) non-layered materials in many aspects differ from their layered counterparts, and the exploration of their physical properties has produced many intriguing findings. However, due to challenges in applying existing experimental techniques to such nanoscale samples, their thermal properties have remained largely uncharacterized, hindering further exploration and device application using this promising material system. Here, we demonstrate an experimental study of thermal conduction in -InS, a typical non-layered 2D material, using a resonant nanoelectromechanical systems (NEMS) platform.

Quantitative regulation of electron-phonon coupling.

Electron-phonon (e-p) coupling plays a crucial role in various physical phenomena, and regulation of e-p coupling is vital for the exploration and design of high-performance materials. However, the current research on this topic lacks accurate quantification, hindering further understanding of the underlying physical processes and its applications. In this work, we demonstrate quantitative regulation of e-p coupling, by pressure engineering andspectroscopy.

Tuning and exploiting interlayer coupling in two-dimensional van der Waals heterostructures.

Two-dimensional (2D) layered materials can stack into new material systems, with van der Waals (vdW) interaction between the adjacent constituent layers. This stacking process of 2D atomic layers creates a new degree of freedom-interlayer interface between two adjacent layers-that can be independently studied and tuned from the intralayer degree of freedom. In such heterostructures (HSs), the physical properties are largely determined by the vdW interaction between the individual layers,interlayer coupling, which can be effectively tuned by a number of means.

Identifying, Resolving, and Quantifying Anisotropy in ReS Nanomechanical Resonators.

As an emerging two-dimensional semiconductor, rhenium disulfide (ReS ) is renowned for its strong in-plane anisotropy in electrical, optical, and thermal properties. In contrast to the electrical, optical, optoelectrical, and thermal anisotropies that are extensively studied in ReS , experimental characterization of mechanical properties has largely remained elusive. Here, it is demonstrated that the dynamic response in ReS nanomechanical resonators can be leveraged to unambiguously resolve such disputes.

Orientation-polarization dependence of pressure-induced Raman anomalies in anisotropic 2D ReS.

We report an high-pressure (0-30.24 GPa) optical study of the 2D ReS crystal under four specific configurations of sample orientation and laser polarization. Unlike the horizontal measurement configuration that has been widely used, under the vertical sample configuration we observe the anomalous disappearance behavior of Raman modes.

Electrically Tunable MXene Nanomechanical Resonators Vibrating at Very High Frequencies.

As an emerging class of two-dimensional (2D) layered nanomaterial, MXene exhibits a number of intriguing properties, such as good electrical conductivity and high elastic modulus, and has witnessed continued growth in related device research. However, nanoscale MXene devices which leverage both the intrinsic electrical and mechanical properties of these 2D crystals have not been experimentally studied. Here we demonstrate nanoelectromechanical resonators based on 2D MXene crystals, where TiCT drumheads with a wide range of thickness, from more than 50 layers all the way down to a monolayer, exhibit robust nanomechanical vibrations with fundamental-mode frequency up to >70 MHz in the very high frequency (VHF) band, a displacement noise density down to 52 fm/Hz, and a fundamental-mode frequency-quality factor product up to × ≈ 6.

Frequency Scaling, Elastic Transition, and Broad-Range Frequency Tuning in WSe Nanomechanical Resonators.

Nanomechanical resonators based on atomic layers of tungsten diselenide (WSe) offer intriguing prospects for enabling novel sensing and signal processing functions. The frequency scaling law of such resonant devices is critical for designing and realizing these high-frequency circuit components. Here, we elucidate the frequency scaling law for WSe nanomechanical resonators by studying devices of one-, two-, three-, to more than 100-layer thicknesses and different diameters.

Analyzing Anisotropy in 2D Rhenium Disulfide Using Dichromatic Polarized Reflectance.

In-plane anisotropy in 2D rhenium disulfide (ReS ) offers intriguing opportunities for designing future electronic and optical devices, and toward such applications, it is crucial to identify the crystal orientation in such 2D anisotropic materials. Existing spectroscopy or electron microscopy methods for determining the crystalline orientation often require complicated sample preparing procedures and specialized equipment, which could sometimes limit their application. In this work, a dichromatic polarized reflectance method is demonstrated, which can quickly and accurately resolve the crystal orientation (Re-Re chain) in 2D ReS crystals with different thicknesses.