Photothermoelectric detection of strain variation in gold nanostructure

Controlling morphology and composition via nanoscale structuring gives opportunities to improve the thermoelectric properties of materials for energy conversion and photodetection. In this study, we report the detection of the strain variation via open circuit photothermoelectric voltage detection on thin-film Au nanowire devices as a function of the position of an optical heat source. A focused laser beam is used to locally heat the metal nanostructure. The first mapping scan of the photothermoelectric voltage shows a relative high value compare with the second scan on the same device after 12 hours annealing. We also conduct a control experiment to shift the work function of the gold nanowire via self-assembled monolayer. Combining the kelvin probe measurement with the photothermoelectric voltage shows the work function variation of the nanowire doesn’t play a key role on the photothermoelectric voltage response. These experiments argue that the strain distribution within the gold nanowire is likely the dominant effect causing the variation of the photothermoelectric voltage. Photothermoelectric voltage measurement provides a sensitive new method to strain distributions within a nanostructured metal.