SENSITIVE UNCOOLED IR DETECTORS USING GALLIUM NITRIDE RESONATORS AND SILICON NITRIDE ABSORBERS

This paper presents the theory and measured results of a lownoise un-cooled infrared (IR) detector, which uses a combination of piezoelectric, pyroelectric, electrostrictive, and resonant effects to achieve high sensitivity.The sensor consists of a high-Q gallium nitride (GaN) micro-mechanical resonator coated with an IR absorber layer.The IR absorber converts the IR energy into heat.The generated heat causes a shift in the frequency characteristics of the GaN resonators.IR detection is achieved by sensing the shift in the resonance frequency of the exposed GaN resonator as compared to a reference resonator.A prototype GaN-based IR sensor is implemented, showing a frequency shift of 400 Hz per µW of absorbed power.The change in the beat frequency upon IR radiation is 1830 ppm/µW, making it possible to sense IR radiation in nano watts range.