Thermal stability and electric properties of Ba 0.7Sr 0.3TiO 3 parallel plate capacitor with nano-Cr interlayer

Abstract

A novel sandwich structure of Ba 0.7Sr 0.3TiO 3/Cr/Ba 0.7Sr 0.3TiO 3 (BST/Cr/BST) was sputtered onto Pt/Ti/SiO 2/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 °C are 4 × 10 − 4 A/cm 2 and 9 × 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 CrO 3 secondary phase after annealing at 700 °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.