CMOS compatible MEMS pyroelectric infrared detectors: from AlN to ScAlN

We present the optical and electrical properties of AlN-based and 12% doped ScAlN-based pyroelectric detectors fabricated on 8-inch wafers respectively. Both AlN and ScAlN materials are deposited at a temperature of ~200oC, making them potential candidates for CMOS compatible MEMS pyroelectric detectors. FTIR spectroscopy is used to measure the absorption of these pyroelectric detectors over the wavelength range of ~2–14 μm and the results show absorption improvement up to ~75% for ScAlN-based pyroelectric detectors compared to that of AlN-based pyroelectric detectors at the wavelength of 4.26 μm where CO2 gas absorption of IR radiation is anticipated. Higher output current (~3-fold increase) is also observed from ScAlN-based pyroelectric detectors. Other than pyroelectric coefficient that contributes to improved performance for ScAlN-based pyroelectric detectors, we believe that absorptivity of the device also plays a major role in the performance of pyroelectric IR detectors. The results obtained from the study of the electrical and optical properties of AlN-based and ScAlN-based CMOS compatible MEMS pyroelectric detectors will bring forth potential applications of these detectors onto multi-functional integrable and monolithic platforms.