pH-sensitive properties of barium strontium titanate (BST) thin films prepared by pulsed laser deposition technique

pH sensitive properties of barium strontium titianate (BST) high k thin films as alternative gate material for field-effect capacitive (bio-) chemical sensors based on an electrolyte-insulator semiconductor system have been investigated. The BST films of different composition (Ba0.3Sr0.69TiO3, Ba0.25Sr0.75TiO3 and MG doped Ba0.8Sr0.2Mg0.1Ti0.9O3 were deposited by pulsed laser deposition technique from targets farbicated by self-propagating high-temperatures synthesis. The realised sensors have been electrochemically characterised by means of impedance-spectroscopy, capacitance-voltage and constant-capacitance method. The sensors possess a Nernstian-like pH sensitivity in the concentration range between pH 3 and 11 with a response time of 5-10 s. An equivalent circuit model for the BST-based capacitive field-effect sensor is discussed.(C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim