# Ultrathin‐Gold‐Resonators‐Enabled Bolometers with High Linearity, Responsivity, and Repeatability

## TL;DR

This paper introduces ultrathin gold nanomechanical resonators that act as highly sensitive and repeatable nanoscale bolometers for laser power sensing.

## Contribution

The novelty lies in demonstrating ultrathin gold resonators with high linearity and responsivity in HF/VHF bands for nanoscale bolometry.

## Key findings

- Ultrathin gold resonators show a nonlinearity factor of 0.0865 and responsivity of ∼−11.47 ppm · µW−1.
- Devices exhibit excellent repeatability across laser power from 2.3 µW to 0.48 mW.
- Frequency scaling law analysis reveals a Young's modulus of 75.6 GPa for ultrathin gold.

## Abstract

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.

This work demonstrates ultrathin gold nanomechanical resonators operating in HF/VHF bands, unveiling their potential for laser power sensing. By exploiting frequency shifts resulting from laser‐induced thermal tension, these devices can function as sensitive nanoscale bolometers, with outstanding linearity, responsivity, and repeatability. The findings also elucidate the frequency scaling law, offering design guidelines for nanoelectromechanical devices based on ultrathin gold material.