Pyroelectric and sensor properties of ferroelectric thin films for energy conversion

High pyroelectric coefficients and improved conversion effects were success fully demonstrated in highly (111)-oriented ferroelectric PZT 90/10 films o n Pt/ Si substrates. The strong preferred orientation exhibited by, these f ilms was obtained through controlled heat-treatment using a specially devel oped MOD process on Pt/Ti/SiO2/Si substrates. Within the FELT-FEHT phase tr ansition range of 80 similar to 100 degrees C, the films exhibited signific ant changes in spontaneous polarization, by roughly a factor of 2 (similar to 7 mu C cm(-2)). A pyroelectric current, correlated to a pyroelectric coe fficient of 30 +/- 10 nC cm(2) K, was obtained around room temperature with out poling treatment. A prototype pyroelectric transformer based on these f ilms gave a voltage output of 0.8 volt from a 1 mm(2) ar ea on a 1.0 mu m t hick film. Compared to bulk ceramics and thick films, these thin films also exhibited at least one order of magnitude higher working frequency. (C) 19 99 Elsevier Science Limited. All rights reserved.