Materials and Processes for MEMS-Based Infrared Microspectrometer Integrated on HgCdTe Detector

Abstract—The materials and processes for fabrication of mono-lithically integrated microelectromechanical systems-based mi-crospectrometers operating in the short-wavelength IR range is presented. Using low-temperature surface micromachining tech-niques, compatible with a range of IR sensor technologies, silicon-nitride-based tunable Fabry–Perot filter structures with dis-tributed Bragg mirrors made of Ge/SiO/Ge layers have been mono-lithically integrated with HgCdTe photoconductors. The stress within and between the many layers of the structure has been elimi-nated or compensated by stress tuning of the deposition conditions. The demonstrated microspectrometers have a tuning range of 1.8– 2.2 µm with relative peak transmission of 70 % and full-width at half-maximum of 80 ± 10 nm. Index Terms—IR detectors, IR filters, microelectromechanical systems (MEMS), microspectrometer