We report the experimental determination of the elastic properties of suspended multilayer WSe₂, a promising two-dimensional (2D) semiconducting material combined with high optical quality. The suspended WSe₂ membranes have been fabricated by mechanical exfoliation of bulk WSe₂ and transfer of the exfoliated multilayer WSe₂ flakes onto SiO₂/Si substrates pre-patterned with hole arrays. Then, indentation experiments have been performed on these membranes with an atomic force microscope. The results show that the 2D elastic modulus of the multilayer WSe₂ membranes increases linearly while the prestress decreases linearly as the number of layers increases. The interlayer interaction in WSe₂ has been observed to be strong enough to prevent the interlayer sliding during the indentation experiments. The Young's modulus of multilayer WSe₂ (167.3 ± 6.7 GPa) is statistically independent of the thickness of the membranes, whose value is about two thirds of other most investigated 2D semiconducting transition metal dichalcogenides, namely, MoS₂ and WS₂. Moreover, the multilayer WSe₂ can endure ∼12.4 GPa stress and ∼7.3% strain without fracture or mechanical degradation. The 2D WSe₂ can be an attractive semiconducting material for application in flexible optoelectronic devices and nano-electromechanical systems.

This report presents a simple and efficient method of layer thinning and p‐type doping of WSe₂ with vapor XeF₂. With this approach, the surface roughness of thinned WSe₂ can be controlled to below 0.7 nm at an etched depth of 100 nm. By selecting appropriate vapor XeF₂ exposure times, 23‐layer and 109‐layer WSe₂ can be thinned down to monolayer and bilayer, respectively. In addition, the etching rate of WSe₂ exhibits a significant dependence on vapor XeF₂ exposure pressure and thus can be tuned easily for thinning or patterning applications. From Raman, photoluminescence, X‐ray photoelectron spectroscopy (XPS), and electrical characterization, a p‐doping effect of WSe₂ induced by vapor XeF₂ treatment is evident. Based on the surface composition analysis with XPS, the causes of the p‐doping effect can be attributed to the presence of substoichiometric WO_x (x < 3) overlayer, trapped reaction product of WF₆, and nonstoichiometric WSe_x (x > 2). Furthermore, the p‐doping level can be controlled by varying XeF₂ exposure time. The thinning and p‐doping of WSe₂ with vapor XeF₂ have the advantages of easy scale‐up, high etching selectivity, excellent controllability, and compatibility with conventional complementary metal‐oxide‐semiconductor fabrication processes, which is promising for applications of building WSe₂ devices with versatile functionalities.

The effect of ${\mathrm{CF}}_4$ gaseous plasma exposure to single-wall carbon nanotubes (CNTs) has been studied. Raman spectroscopy results show that CNTs have gained more disordered ${\mathrm{sp}}^3$ bonds associated with functionalization, as both the flow rates of gas in the plasma and exposure time in the plasma are increased. Scanning electron microscopy images indicate the CNTs have been preserved after ${\mathrm{CF}}_4$ plasma exposure. X-ray photoelectron spectroscopy provides evidence of carbon to fluorine bonds (C–F) on the CNTs samples after ${\mathrm{CF}}_4$ plasma exposure. Semi-ionic and covalent C–F bonds are prevalent on the CNTs after ${\mathrm{CF}}_4$ exposure with the intensity ratio of the semi-ionic to covalent C–F bond decreasing as the flow rate of ${\mathrm{CF}}_4$ and exposure time in the ${\mathrm{CF}}_4$ plasma is increased.

4H silicon carbide (SiC) substrates were dry etched in an inductively coupled plasma (ICP) system, using ${\mathrm{SF}}_6/{\mathrm{O}}_2$ gas mixtures. Etch rate and etch mechanisms have been investigated as a function of oxygen concentration in the gas mixture, ICP chuck power, work pressure, and flow rate. Corresponding to these etch conditions, surface information of the etched SiC has been obtained by x-ray photoelectron spectroscopy measurements. The fact that no obvious Si–Si and Si–F bonds were detected on the etched surface of SiC in all our etch experiments suggests efficient removal of Si atoms as volatile products during the processes. However, various kinds of C–F bonds have been detected on the etched SiC surface and the relative intensities of these bonds vary with the etch conditions. In addition, the nature of the incorporated F atoms on the etched surface also depends strongly on etch conditions, which was identified by the change of the relative ratio between semi-ionic and covalent carbon fluorine bonds. The electrical behavior for different bond structures on the etched SiC surface can be one of the basic reasons affecting related devices.

The addition of piezoelectric zinc oxide (ZnO) fillers into a flexible polymer matrix has emerged as potential piezocomposite materials that can be used for applications such as energy harvesters and pressure sensors. A simple approach for the fabrication of PDMS-ZnO piezoelectric nanocomposites based on two ZnO fillers: nanoparticles (NP) and nanoflowers (NF) is presented in this paper. The effect of the ZnO fillers’ geometry and size on the thermal, mechanical and piezoelectric properties is discussed. The sensors were fabricated in a sandwich-like structure using aluminium (Al) thin films as top and bottom electrodes. Piezocomposites at a concentration of 10% w/w showed good flexibility, generating a piezoelectric response under compression force. The NF piezocomposites showed the highest piezoelectric response compared to the NP piezocomposites due to their geometric connectivity. The piezoelectric compound NF generated 4.2 V while the NP generated 1.86 V under around 36 kPa pressure. The data also show that the generated voltage increases with increasing applied force regardless of the type of filler.