Uncooled Infrared Detectors Using Gallium Nitride on Silicon Micromechanical Resonators

This paper presents the analysis, design, fabrication, and the first measured results demonstrating the use of gallium nitride (GaN)-based micromechanical resonator arrays as high-sensitivity, low-noise infrared (IR) detectors. The IR sensing mechanism is based on monitoring the change in the resonance frequency of the resonators upon near IR radiation. The resonators are characterized for their RF and thermal performance and exhibit a radiant responsivity of 1.68%/W, thermal time constant on the order of 556 μs, and an average IR responsivity of -1.5% when compared with a reference resonator, for a 100 mK radiation-induced temperature rise. An analysis of the design of the devices is presented as a path toward better design, specifically, for low thermal noise equivalent temperature difference in the long wavelength IR spectrum.