Experimental Study of Spectrally Selective MEMS/Metasurface Infrared Detectors

This article reports a comprehensive statistical analysis of uncooled infrared (IR) detectors based on radio frequency (RF) aluminum nitride (AlN) contour mode resonators (CMRs) integrated with spectrally selective IR metasurfaces. Moreover, it reports the lowest noise equivalent power (NEP) recorded from these types of devices (
$\sim $
11 pW
$/\sqrt {\text {Hz}}$
). The metasurfaces are printed on top of the AlN resonator body to decouple mechanical, RF, and IR responses. Optical lithography is used to pattern the metasurfaces, allowing the fabrication of hundreds of spectrally selective IR detectors with different sensing performances within the same chip. An automated characterization system is employed to quickly record parameters such as quality factor, noise, and responsivity. This approach allows to experimentally determine the geometrical dimensions of quasi-optimal IR detectors that exhibit NEP in the pW
$/\sqrt {\text {Hz}}$
range and responsivities in the Hz/nW range. Additionally, the detector performance versus IR light is explored using different interrogation mechanisms, namely monitoring the CMR resonance frequency as well as the amplitude and phase of an RF signal that excites the device at resonance. The statistical analysis of hundreds of IR sensors reveals trends between parameters such quality factor and noise floor, and NEP and responsivity. These trends provide useful guidelines for the development of quasi-optimal spectrally selective IR sensors operating at room temperature.