Influence of Ta_2O_5, TiO_2, and ZrO_2 Interfacial Layers on Structural and Electrical Properties of Laser Ablated Ba_(0.5)Sr_(0.5)TiO_3 Thin Films

摘要

Pulsed laser deposition technique was used to fabricate Ba_(0.5)Sr_(0.5)TiO_3 (BST) thin-films on Pt/TiO_2/SiO_2/Si substrates. The influence of thin interfacial layers of Ta_2O_5, TiO_2, and ZrO_2, on the structural and electrical properties of BST thin films was investigated. Insertion of interfacial layers does not affect the perovskite phase formation of BST thin films. Buffer layers helped to make uniform distribution of grains and resulted in a relative increase in the average grain size. The dielectric tunability of BST thin films was reduced with the presence of buffer layers. A BST thin film having a dielectric permitivity of 470 reduced to 337, 235 and 233 in the presence of Ta_2O_5, TiO_2, and ZrO_2 layers, respectively. The reduction of the relative dielectric permittivity of BST films with the insertion of interfacial layers was explained in terms of a series capacitance effect, due to the low dielectric constant of interfacial layers. The TiO_2 layer did not show any appreciable change in the leakage current deasity. Deposition of thin Ta_2O_5 and ZrO_2 interfacial layer on top of R reduced the leakage current density by an order of magnitude.