Electrical properties of compositionally graded lead calcium titanate thin films

The compositional gradient (Pb1-xCax)TiO3 (PCT) thin films of x = 0 and 24 mol% were fabricated on Pt/Ti/SiO2/Si substrates by using a modified sol-gel process. The final structure consists of two layers, up-graded films starting from PbTiO3 on the Pt electrode to the top PCT(24) layer, whereas films with opposite gradient are called down-graded films. Highly (100)-oriented graded PCT thin films have been obtained when the graded PCT thin films were annealed at 600degreesC.At 100 kHz, the dielectric constants were 79 and 128, respectively, for the up-graded and down-graded PCT films. The pyroelectric coefficient (p) of the graded films was measured by a dynamic technique. At room temperature, the values of p and figure-of-merits (F-D) of the up-graded and down-graded PCT films are 95muC/m(2) K and 9.1 x 10(-6) Pa-0.5, 112muC/m(2) K and 8.6 x 10(-6) Pa-0.5, respectively. (C) 2003 Elsevier Ltd. All rights reserved.