Heat Flow and Detectivity of Multilayer Thin-Film Pyroelectric Detector

The pyroelectric responses of a multilayer, thin-film pyroelectric detector under both isolated and heat-sink boundary conditions are completely analyzed. Exact mathematical solutions of the heat flow equation are derived. The multilayer detector is composed of pyroelectric layer/thermal isolation layer/silicon substrate. The analytical result shows that when the thickness of the isolation layer is increased, the detectivity, D *, at low frequencies will be improved, and as the thickness of the pyroelectric layer is decreased, the high-frequency response is improved. D * of a detector with 1 µm PLZT((Pb, La)(Zr, Ti)O3)/10 µm porous silica/0.5 mm silicon is higher than that of the detector with 10 µm PLZT/1 µm porous silica/0.5 mm silicon in a wide frequency range. In order to achieve better performance of a multilayer thin-film detector, the thicknesses of the two layers should be chosen very carefully. This analysis provides a guide for the preparation of multilayer thin-film pyroelectric detectors.