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Abstract Surface acoustic waves (SAWs) propagate along solid-air, solid-liquid, and solid-solid interfaces. Their characteristics depend on the elastic properties of the solid. Combining transmission electron microscopy (TEM) experiments with molecular dynamics (MD) simulations, we probe atomic environments around intrinsic defects that generate SAWs in vertically stacked two-dimensional (2D) bilayers of MoS2. Our joint experimental-simulation study provides insights into SAW-induced structural and dynamical changes and thermomechanical responses of MoS2bilayers. Using MD simulations, we compute mechanical properties from the SAW velocity and thermal conductivity from thermal diffusion of SAWs. The results for Young’s modulus and thermal conductivity of an MoS2monolayer are in good agreement with experiments. The presence of defects, such as nanopores which generate SAWs, reduces the thermal conductivity of 2D-MoS2by an order of magnitude. We also observe dramatic changes in moiré patterns, phonon focusing, and cuspidal structures on 2D-MoS2layers.
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Electrically Tunable Surface Acoustic Wave Propagation at MHz Frequencies Based on Carbon Nanotube Thin‐Film Transistors
Abstract Surface acoustic waves (SAWs) that propagate on the surface of a solid at MHz frequencies are widely used in sensing, communication, and acoustic tweezers. However, their properties are difficult to be tuned electrically, and current devices suffer from complicated configurations, complicated tuning mechanisms, or small ranges of tunability. Here a structure featuring a thin‐film transistor configuration is proposed to achieve electrically tunable SAW propagation based on conductivity tuning. When a DC gate voltage is applied, the on‐site conductivity of the piezoelectric substrate is modulated, which leads to velocity and amplitude tuning of SAWs. The use of carbon nanotubes and crystalline nanocellulose as the channel and gate materials results in high tuning capacity and low gate voltage requirement. The tunability is manifested by a 2.5% phase velocity tuning and near 10 dB on/off switching of the signals. The proposed device holds the potential for the next generation SAW‐based devices.
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- PAR ID:
- 10376156
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 31
- Issue:
- 18
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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