Chemical solution deposition of BaSrTiO₃ films

Abstract

We compared three chemical solution deposition routes to BaxSr1-xTiO3 (BST) films. A metal organic decomposition (MOD) solution composed of barium and strontium acetate, titanium diisopropoxide bis(acetylacetonate), dissolved in a mixture of acetic acid, water and isoproponal resulted in films with spin defects, pinholes, poor crystallization, and poor electrical properties. FTIR spectra revealed a less facile decomposition pathway as indicated by the larger thermal budget required to decompose the titanium precursor, a reduced hydroxy component and increased free CO2. A hybrid route utilizing acetic acid modified barium, strontium and titanium isopropoxides resulted in films with better crystallinity and a reduced carbonate content in the FTIR spectra. The best BST films were obtained from a sol gel route utilizing barium, strontium and titanium 2-methoxyethoxides. The films had minimal carbonate content in the FTIR spectra, crystallized at 700 °C, and had dielectric constants up to 400 with leakage currents less than 10-7 A/cm2.