Thermal stability and electric properties of Ba0.7Sr0.3TiO3 parallel plate capacitor with nano-Cr interlayer

Abstract

A novel sandwich structure of Ba0.7Sr0.3TiO3/Cr/Ba0.7Sr0.3TiO3 (BST/Cr/BST) was sputtered onto Pt/Ti/SiO2/Si substrate. With the insertion of a Cr layer, the leakage currents are decreased and the thermal stability of the specimens is enhanced. Temperature coefficient of capacitance (TCC) of specimens with BST(200 nm)/Cr(2 nm)/BST(200 nm) multifilms can achieve about 83% lower than those with BST (400 nm) monolayer. However, the dielectric constant of the BST(200 nm)/Cr(2 nm)/BST(200 nm) multifilms decreases to about 37% of that BST monolayer. The leakage current densities under an electric field of 125 kV/cm at 90 degrees C are 4 x 10(-4) A/cm(2) and 9 x 10(-1) A/cm(2) for BST(200 nm)/Cr(2 nm)/BST(200 nm) and monolayer BST (400 nm), respectively. X-ray diffraction results indicate the formation of a CrO3 secondary phase after annealing at 700 degrees C or above in O-2 atmosphere. The root causes for the improvement of leakage currents and thermal stability with the insertion of nano-Cr interlayer are explored. The results show the insertion of Cr-nanolayer improves the electric properties for application in capacitors. (c) 2006 Elsevier B.V All rights reserved.