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

The materials and processes for fabrication of monolithically integrated microelectromechanical systems-based microspectrometers operating in the short-wavelength IR range is presented. Using low-temperature surface micromachining techniques, compatible with a range of IR sensor technologies, silicon-nitride-based tunable Fabry–Perot filter structures with distributed Bragg mirrors made of Ge/SiO/Ge layers have been monolithically integrated with HgCdTe photoconductors. The stress within and between the many layers of the structure has been eliminated or compensated by stress tuning of the deposition conditions. The demonstrated microspectrometers have a tuning range of 1.8–2.2 $\mu$m with relative peak transmission of 70% and full-width at half-maximum of 80 $\pm$ 10 nm.