Thickness effects on the pyroelectric properties of chemical-solution-derived Pb(Zr-0.3,Ti-0.7)O-3 thin films for the infra-red sensor devices

Abstract

The pyroelectric and dielectric properties of Pb(Zr-0.3,Ti-0.7)O-3 (PZT) thin films are systematically investigated as functions of film thickness ranging from, 0.3 to 1 mum. For better detectivity of the film, high pyroelectric coefficient, low dielectric coefficient and. loss tangent are needed. It can be achieved by highly textured (111) preferred orientation and dense microstructure. To minimize the unwanted preferred orientation with increasing film thickness, a step-by-step annealing process and highly textured (111) Pt bottom electrodes are applied. With increasing film thickness, the squareness of polarization hysteresis loops and remanent polarization values are maximized. Although there is a slight variation of preferred orientation with film thickness, dielectric properties are markedly changed due to microstructural variation. Because of the large improvement of loss tangent, the figure of merit is improved with film thickness. It is maximized at a thickness of 1 mum. The maximum pyroelectric coefficient measured by the Byer-Roundy method is 38 nC/cm(2)K.