Calculation of the intrinsic dead layers thicknesses from Au/Ba0.5Sr0.5TiO3/Pt thin film capacitors

Abstract

Ferroelectric Ba 0.5 Sr 0.5 TiO 3 (BST) films were prepared on Pt/Ti/SiO 2 /Si substrates by the sol-gel process. The films were spin-coated at 2000 rpm for 30 secs and then pyrolysed for 5 mins at the temperature of 350 • C. This coating procedure was repeated for 3, 4, 5 and 6 times to obtain BST films with different thicknesses. After coating the films with the desired repetition times, the films were finally annealed in a conventional furnace at temperatures ranging from 600 • C to 800 • C with a 50 • C interval in between. The films obtained with an annealing procedure of 750 • C were polycrystalline with the presence of an impurity BaCO 3 phase. The capacitance and leakage current were measured and used to extract information on the metal-BST interface. With the series capacitance model and modified Schottky emission equation, the thickness of the dead layers for Au/BST and Pt/BST interfaces were calculated to be less than 6 nm and 5 nm, respectively.