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 (Pb 0.925 La 0.075 )(Zr y Ti 1- 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, F.M. 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 F.M. for voltage responsivity Rv of approximately 5.3×10 -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 µm diameters were suitable for the measurement of pyroelectric properties, judging from the characteristics of the materials and the accuracy of the measuring instruments.