Ultrathin-Gold-Resonators-Enabled Bolometers with High Linearity, Responsivity, and Repeatability.

Ultrathin metal films, with thickness down to just a few nanometers, boast unique optical and electronic properties compared with bulk metals, and show great potential in advanced sensing applications. Incorporating mechanical degrees of freedom would offer a promising route toward further enriching their sensing capabilities, yet this possibility has been rarely explored to date. Here, we demonstrate ultrathin gold nanomechanical resonant sensors with robust vibrations in the high frequency (HF) and very high frequency (VHF) bands. We show that such devices can function as nanoscale bolometers with good linearity (nonlinearity factor of 0.0865), high power-to-frequency responsivity (∼-11.47 ppm · µW⁻¹), and excellent repeatability across a broad range of laser power (2.3 µW-0.48 mW). We further elucidate the frequency scaling law of these resonant sensors, extracting a Young's modulus of 75.6 GPa for the ultrathin gold crystal and a device pretension of 0.09-0.8 N · m⁻¹. Our work paves the way toward future wafer-scale design and on-chip integrated sensors based on ultrathin metal nanomechanical devices.