Gallium sulphide (GaS), gallium selenide (GaSe), and gallium telluride (GaTe), belonging to the group-III monochalcogenide family, have shown promising optoelectronic performance over graphene and monolayer molybdenum disulphide (MoS2). However, to date, the mechanical properties of these materials have not been investigated, which hinders their utilisation in flexible electronics and optomechanics. Here, we characterize the elastic properties and breaking strengths of suspended two-dimensional (2D) nanosheets of GaS, GaSe, and GaTe, using atomic force microscopy. The 2D Young's modulus values of ∼10 nm thick GaS, GaSe, and GaTe were found to be 1732 ± 154 N m-1, 819 ± 127 N m-1, and 246 ± 160 N m-1, respectively, corresponding to the three-dimensional (3D) Young's modulus values of 173 ± 15 GPa, 81.9 ± 12.7 GPa, and 24.6 ± 16 GPa, respectively. The pre-tension values of these nanosheets were estimated to be 0.34 ± 0.12 N m-1, 0.14 ± 0.04 N m-1, and 0.15 ± 0.03 N m-1 for GaS, GaSe, and GaTe, respectively. GaS nanosheets exhibited the highest Young's modulus (173 GPa) among these nanosheets, which is comparable to that of WS2 and WSe2. A failure characteristic study over these group-III monochalcogenides revealed that these materials can withstand stresses of up to 8 GPa and a maximal strain of 7% before breaking. Altogether, our findings indicate that GaS, GaSe, and GaTe are attractive candidates for use in stretchable electronic applications and in future optomechanical devices.

We study for the first time the resonant torsional behaviors of inorganic nanotubes, specifically tungsten disulfide (WS) and boron nitride (BN) nanotubes, and compare them to that of carbon nanotubes. We have found WS nanotubes to have the highest quality factor (Q) and torsional resonance frequency, followed by BN nanotubes and carbon nanotubes. Dynamic and static torsional spring constants of the various nanotubes were found to be different, especially in the case of WS, possibly due to a velocity-dependent intershell friction. These results indicate that inorganic nanotubes are promising building blocks for high-Q nanoelectromechanical systems (NEMS).

No abstract

The integration of suspended carbon nanotubes into micron-scale silicon-based devices offers many exciting advantages in the realm of nano-scale sensing and micro-and nano-electromechanical systems (MEMS and NEMS). To realize such devices, simple fabrication schemes are needed. Here we present a new method to integrate carbon nanotubes into silicon-based devices by applying conventional micro-fabrication methods combined with a guided chemical vapor deposition growth of single-wall carbon nanotubes. The described procedure yields clean, long, taut and well-positioned tubes in electrical contact to conducting electrodes. The positioning, alignment and tautness of the tubes are all controlled by the structural and chemical features of the micro-fabricated substrate. As the approach described consists of common micro-fabrication and chemical vapor deposition growth procedures, it offers a viable route toward MEMS-NEMS integration and commercial utilization of carbon nanotubes as nano-electromechanical transducers.

Gallium telluride (GaTe) is a layered material, which exhibits a direct bandgap (∼1.65 eV) regardless of its thickness and therefore holds great potential for integration as a core element in stretchable optomechanical and optoelectronic devices. Here, we characterize and demonstrate the elastic properties and electromechanical resonators of suspended thin GaTe nanodrums. We used atomic force microscopy to extract the Young's modulus of GaTe (average value ∼39 GPa) and to predict the resonance frequencies of suspended GaTe nanodrums of various geometries. Electromechanical resonators fabricated from suspended GaTe revealed fundamental resonance frequencies in the range of 10-25 MHz, which closely match predicted values. Therefore, this study paves the way for creating a new generation of GaTe based nanoelectromechanical devices with a direct bandgap vibrating element, which can serve as optomechanical sensors and actuators.