12 April 1996 Sol-gel-derived lead and calcium lead titanate pyroelectric detectors on silicon MEMS structures
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Abstract
Pyroelectric detectors based on PbTiO3 (PTO) and Pb1-xCaxTiO3 (PCTx) were fabricated and evaluated on thin silicon micro electrical-mechanical structures (MEMS) utilizing a new sol-gel technique. The sol-gel approach allows arbitrary Pb:Ca ratio, and is fully compatible with existing CMOS processes. The novel precursor chemistry developed in our laboratory is not moisture sensitive, and has a shelf-life of many months. Layers of PTO precursor were spin-coated onto 4 micrometers thick silicon membrane structures. Heat treatment at 700 degree(s)C yielded crack-free films approximately 0.3 micrometers thick. Contacts to the top of the pyroelectric film and to the silicon membrane were made by thermal evaporation of aluminum. The reduced thermal capacitance and improved thermal isolation offered by the MEMS membrane structure have significantly improved the performance of our device over typical bulk single crystal or ceramic devices. Pyroelectric responsivity of 2.5 volt/watt was measured at (lambda) equals 10.6 micrometers for a first generation simple membrane structure without poling or electrical bias. SPICE analysis of a distributed thermal circuit model indicates the potential for two orders of magnitude improvement in device sensitivity for optimized membrane structures currently under construction. These results also indicate that a fully integrated high-performance room temperature imaging array for use in the far IR can be realized at low cost.
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James G. Ho, James G. Ho, Phyllis R. Nelson, Phyllis R. Nelson, Felice H. Lin, Felice H. Lin, David T. Chang, David T. Chang, William J. Kaiser, William J. Kaiser, Oscar M. Stafsudd, Oscar M. Stafsudd, } "Sol-gel-derived lead and calcium lead titanate pyroelectric detectors on silicon MEMS structures", Proc. SPIE 2685, Photodetectors: Materials and Devices, (12 April 1996); doi: 10.1117/12.237693; https://doi.org/10.1117/12.237693
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