Pyroelectric and sensor properties of ferroelectric thin films for energy conversion

High pyroelectric coefficients and improved conversion effects were successfully demonstrated in highly (111)-oriented ferroelectric PZT 90/10 films on Pt/ Si substrates. The strong preferred orientation exhibited by, these films was obtained through controlled heat-treatment using a specially developed MOD process on Pt/Ti/SiO2/Si substrates. Within the FELT-FEHT phase transition range of 80 similar to 100 degrees C, the films exhibited significant changes in spontaneous polarization, by roughly a factor of 2 (similar to 7 mu C cm(-2)). A pyroelectric current, correlated to a pyroelectric coefficient of 30 +/- 10 nC cm(2) K, was obtained around room temperature without poling treatment. A prototype pyroelectric transformer based on these films gave a voltage output of 0.8 volt from a 1 mm(2) ar ea on a 1.0 mu m thick film. Compared to bulk ceramics and thick films, these thin films also exhibited at least one order of magnitude higher working frequency. (C) 1999 Elsevier Science Limited. All rights reserved.