Preparation and Characterization of Ba x Sr 1‐x , TiO 3 Thin Films by a Sol‐Gel Technique

Abstract

Barium strontium titanate, (Ba x ,Sr 1‐x TiO 3 , thin films of various compositions were prepared by a sol‐gel method. Solutions consisting of acetate powders and titanium IV isopropoxide in a mixture of acetic acid and ethylene glycol were spin‐coated onto silicon and platinum‐coated silicon substrates. Processing parameters were optimized to develop stable solutions which yielded films with relatively low crystallization temperatures. It was determined that ethylene glycol was a necessary component of the solution to increase stability to precipitation and to decrease the crystallization temperature of the films. The grain size of the films varied with annealing temperature and atmosphere and directly affected the dielectric properties. A dielectric constant of 400 and a dissipation factor of 0.04 were measured at 1 kHz for (Ba 0.8 ,Sr 0.2 ) TiO 3 films heated to 700°C for 1 h with a thickness of approximately 400 nm. Films of this composition maintained low leakage current densities for extended time periods when measured at an applied field of 75 kV/cm.