High Sensitivity Long-Wave Infrared Detector Design Based on Integrated Plasmonic Absorber and VO₂ Nanobeam

We report a novel design for bolometric infrared detector operating at the long-wave infrared (LWIR) range for high-resolution human body temperature sensing and monitoring. We propose to incorporate efficient plasmonic absorber and high-responsivity VO2 nanobeam biased at transition temperature in our design to facilitate improvement in both aspects – thermal resolution and spatial resolution. The integration of plasmonic absorber allows efficient and selective radiation absorption. The use of a transducing nanobeam placed in close proximity to the plasmonic local heaters allows the radiation energy to be electronically readable. The use of nanobeam instead of a film in the detector allows over two-orders of magnitude improvement in responsivity owing to the large length to cross-sectional area ratio. Additionally, the use of nanobeam reduces the thermal mass and improves the bandwidth. Our calculation suggests a responsivity of as high as 700 kV/W at 100 Hz for a detector of only $12\,\,\mu \text{m}\,\,\times 12\,\,\mu \text{m}$ pixel size. Also, the theoretical noise equivalent temperature difference is calculated to be as low as 3.67 mK which is almost an order of improvement than the state-of-the-art bolometric LWIR detectors with larger pixel dimensions.