Shape engineering of antenna-coupled single-metal nanothermocouples

We study the thermal response of antenna-coupled nanothermocouples (NTC) for long-wave infrared (IR) detection based on a single-metal nanostructure and shape engineering. The influence of the shape of the NTC junctions on the electrical and IR response of the sensor is studied. In particular, we compare detectors with abrupt and tapered junctions. We find that the thermoelectric behaviors of the two different NTC designs are identical when one of the junctions is selectively heated by a nanoscale heater to produce an open-circuit voltage. However, the IR responses are significantly different when the junctions are heated by the radiation-induced antenna current. Both simulations and experiments demonstrate that the tapered junction is more efficiently heated by the antenna, which results in nearly twice as large IR response compared with detectors having abrupt junctions.