Relationship between pyroelectric properties and electrode sizes in (Pb,La)(Zr,Ti)O3 (PLZT) thin films

Highly c-axis-oriented PLZT films with compositions of (Pb0.925La0.075)(ZryTi1-y)(0.981)O-3, where y = 0.2-0.4, were deposited on Pt(100)/MgO(100) by the rf-magnetron sputtering, applying an intermittent deposition comprised of the repetition of deposition and nondeposition. It was confirmed that the highest figures of merit, EM. and F.M.D* for the pyroelectric IR sensors were obtained by using powders with excess PbO of 20 mol% added to PLZT, as sputtering targets in the preliminary experiment. The PLZT film with y = 0.2 exhibited the highest EM. for voltage responsivity Rv of approximately 5.3 x 10(-13) C . m/J among the three samples studied, which was around 1.8 times larger than that of PLZT ceramic with y = 0.2. The top-electrode sizes of around 500 and 250 mu m diameters were suitable for the measurement of pyroelectric properties, judging from the characteristics of the materials and the accuracy of the measuring instruments.