Influence of Space Charge Layers on the Dielectric Properties of Ba0.6 Sr0.4TiO3 Nanostructured Thin Films

Barium strontium titanate (Ba0.6Sr0.4TiO3) nanostructured thin films have been deposited on platinized silicon substrates by the sol-gel method. The as-fired films were found to be amorphous, which crystallize to cubic phase after annealing at 550°C in air for one hour. The low-frequency dielectric responses of the BST films were measured as functions of frequency range from 1 kHz to 1MHz. The thickness dependence dielectric constant of the BST thin films were measured in the temperature range from −150°C to 150°C at 100 kHz and discussed in the light of an interfacial dead layer. All the samples showed a diffuse type phase transitions. Both the dielectric constant and loss tangent showed anomaly peaks at about 10°C, which corresponds to a tetragonal ferroelectric-to-cubic paraelectric phase transition.