Pyroelectric Properties of La-Sr-Co-O/Pb-La-Ti-O/La-Sr-Co-O Heterostructures
Abstract
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 La(x)Sr(1-x)CoO(3) (LSCO). In addition to being crystallographically compatible with the lead-based pyroelectric oxides such as Pb(0.9)La(0.1)Ti(0.975)O(3) (PLTlO) 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/PLTl0/LSCO on single- crystal LaAlO(3) substrates by pulsed laser deposition. By care fully 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 (alpha=10 to the 5th/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/cm(2)K for PLTlO. Both pyroelectric coefficients and pulsed polarization values show a clear dependence on the c-axis volume fraction of the PLTl0 films. Finally the Byer-Roundy technique is being used to study the impact of electronic defects on the pyroelectric response of these heterostructures.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1999
- Accession Number
- ADA390130
Entities
People
- C. W. Tipton
- D. N. Robertson
- R. C. Hoffman
- R. P. Godfrey
- T. Friessnegg
Organizations
- United States Army Research Laboratory