Ultrasound Tip-Assisted Piezotronic Transduction in Monolayer MoS₂

The interaction of ultrasonic waves with piezoelectric materials provides a quantitative route to enhance electrical and mechanical coupling in van der Waals (vdW) heterostructures. Here, wire-bonding tip-assisted ultrasound (≈100 kHz) is presented as an effective approach to achieve piezoelectric transduction in monolayer MoS₂ on Si/SiO₂ substrates. Transient current measurements show reproducible sharp peaks with a peak-to-base ratio (I_peak/I_base ≈ 12) unique to monolayer MoS₂, under an impact duration of 10-100 ms. Electrostatic gate voltage (V_g) and ultrasound power (W_P) tunable piezocurrent exhibit 3-5 times higher sensitivity in the ON-state (V_g ⩾ 0) compared to the OFF-state. Multiple reflections of acoustic waves at source-drain electrodes, with an increment in reflection coefficients, enhance the linewidth of peak currents, validated by microacoustic simulations of surface acoustic wave (SAW) propagation in submicron geometries. The localized strain and Joule heating under ultrasonic excitation may generate a temperature rise of ≈20 K, which reduces activation energy barriers, potentially enhancing reaction rates in temperature-sensitive chemical processes, such as hydrogen peroxide decomposition. This thermal-damage-free method integrates with silicon-based fabrication, establishing a robust platform for on-chip catalysis and energy harvesting in FET-based piezotransducers.