Dielectric properties and I-V characteristics of (Pb0.4Sr0.6)TiO3 thin films improved by TiO2 buffer layers

Abstract

A TiO2 thin buffer layer was introduced between the (Pb0.4Sr0.6)TiO3 (PST) film and the Pt/Ti/SiO2/Si substrate in an attempt to improve their electrical properties. Both TiO2 and PST layers were prepared by a chemical solution deposition method. It was found that the TiO2 buffer layer increased the (100)/(001) preferred orientation of PST and decreased the surface roughness of the films, leading to an enhancement in electrical properties including an increase in dielectric constant and in its tunability by DC voltage, as well as a decrease in dielectric loss and leakage current density. At an optimized thickness of the TiO2 buffer layer deposited using 0.02 mol/l TiO2 sol, the 330-nm-thick PST films had a dielectric constant, loss and tunability of 1126, 0.044 and 60.7% at 10 kHz, respectively, while the leakage current density was 1.95 × 10−6 A/cm2 at 100 kV/cm.