Development of Au-Pt Buffer Layer Substrate to Improve PZT Piezoelectric Property

Abstract

In this study, high piezoelectric lead zirconate titanate (PZT) thin film was prepared with MPB (Morphotoropic Phase Boundary) composition and buffer layer. From our previous study, high piezoelectricity of PZT thin film was confirmed through MPB (Morphotoropic Phase Boundary) composition and also noted that the piezoelectricity becomes maximum when PZT (111) and PZT (110) thin films stacked evenly. MPB composition and buffer layer significantly reduces the lattice mismatch to attain maximum piezoelectricity. It has been already reported that Au (111) and Pt (111) take high priority to orient PZT thin film in (111) and (110) crystal planes respectively. Therefore, the purpose of this study is to create alternately oriented buffer layer of Au (111) and Pt (111) and its influence on crystal quality.Sputtering technique was used to deposit Au-Pt buffer layer on Si substrate. Due to natural oxidation of Si in air atmosphere, the growth orientation of the thin film may be affected. Hence, prior to deposition, Si substrate was washed with hydrofluoric acid to remove the natural oxidation film. Further using Au-Pt composite target, buffer later was deposited on Si substrate and consequently the film was annealed. As a result of Au-Pt buffer layer 127 % of increase in crystal quality was observed as compared with the film deposited without buffer layer.