Effective Temperature Sensing by Irreversible Morphology Evolution of Ultrathin Gold Island Films

An ultrathin gold island film is developed showing efficient temperature sensing when maintaining at certain duration and may be a potential candidate as a temperature marker. The developed gold thin film is based on the energy minimization principle, in which unstable ultrathin films experience morphological instability and self-organization upon thermal dewetting, providing the finger print for recording the temperature and duration of the thermal event based on their variation of characteristic optical properties. As compared with other temperature sensing mechanisms and nanostructures, the ultrathin gold film displays an irreversible variation that may be employed ex-situ for extreme conditions in which in situ measurements of the thermal history may not be feasible. A high sensitivity is possible for temperature sensing even at temperatures as low as 100 degrees C when the time is fixed due to an efficient dewetting process at the nanoscale. This Au-based nanostructure allows fast readout of temperature by simply measuring the surface plasmon absorption. The thermal model was developed based on the correlation among the optical properties, morphological evolution, and the dewetting dynamics and validated with experimental data with accurate determination of temperature within an uncertainty of 4%. The thickness-dependent dewetting behavior further opens up the possibility for designing various nanostructures with controllable sensitivities by simple manipulation of the film thickness and thus dewetting dynamics.