PYROELECTRIC PROPERTIES OF La-Sr-Co-O/Pb-La-Ti-O/La-Sr-Co-O HETEROSTRUCTURES

The realization of a commercially viable, thin-film uncooled pyroelectric detector has been the focus of research for several years. As part of this effort, we show that a conventional metallic electrode system (typically Pt) can be replaced with a conductive oxide such as LaxSr(1–x)CoO3 (LSCO). In addition to being crystallographically compatible with the lead-based, pyroelectric oxides such as Pb0.9La0.1Ti0.975O3 (PLT10), LSCO is also chemically compatible, which aids in reducing the energy barrier for oriented growth and promotes the formation of phase-pure perovskite pyroelectric material. We have grown pyroelectric heterostructures of LSCO/PLT10/LSCO on singlecrystal LaAlO3 substrates by pulsed laser deposition. By carefully optimizing the processing conditions, we are able to obtain high-quality, thin films that allow us to investigate the basic pyroelectric properties of this material system. Additionally, LSCO exhibits a strong infrared absorption (α== 10/cm), which is beneficial for producing a simplified detector design with enhanced performance. We will discuss the pyroelectric and dielectric properties of LSCO/PLT10/LSCO heterostructures and their dependence on microstructure. Structural characterizations reveal that the c-axis orientation of the PLT10 can be maximized. Pyroelectric measurements using the Byer-Roundy method have yielded, on the average, pyroelectric coefficients of 50 nC/cmK for PLT10. Both pyroelectric coefficients and pulsed polarization values show a clear dependence on the c-axis volume fraction of the PLT10 films. Finally, the Byer-Roundy technique is being used to study the impact of electronic defects on the pyroelectric response of these heterostructures.