Enhanced-response pyroelectric heterostructures

We have observed enhanced pyroelectric responses in sub-100 nm, epitaxial P b-Zr-Ti-O films contacted with conducting perovskite oxide top and bottom e lectrodes. These enhancements are obtained in capacitors where the bottom e lectrode is processed under reducing conditions. This leads to an asymmetri c, temperature-dependent internal electric field that is produced within th e ferroelectric capacitor and manifests itself as a strongly shifted ferroe lectric hysteresis loop. Because the shifted coercive voltage lies near the unbiased operating point, the pyroelectric film has a large value of dP/dE . The product (dP/dE)/(dE/dT) gives rise to an enhanced pyroelectric respon se. Our data show that a 10-30 times increase in the pyroelectric response can be obtained over symmetric devices, with a concomitant improvement of t he sensing figure-of-merit by three times. (C) 2000 American Institute of P hysics. [S0003-6951(00)02941-7].