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Abstract
The choice of the material and an optimal thermal isolation of the sensitive elements are essential for a pyroelectric sensor with high detectivity. In this paper the application of two different ferroelectric materials, a copolymer [poly(vinylidene fluoride/trifluoroethylene), P(VDF/TrFE)] and a ceramic thin film (PZT) for pyroelectric IR sensing, is discussed. The polymer has a low Curie temperature (between 49°C and 135°C) and hence there is a risk of depolarization at temperatures higher than room temperature. In comparison PZT with a Zr content of 25 at% has a high Curie temperature (450°C) and the sputtered films exhibit self-polarization. Single element sensors fabricated from both materials, with a radiation sensitive area of 1 mm2 on SiO2/Si3N4 membranes exhibit at room temperature a specific detectivity of about 3×108 cm Hz½W−1. In addition, sensor arrays with up to 128 elements were also fabricated.
