Real-time observations of interface formation for barium strontium titanate films on silicon

Abstract

Ba .5 Sr .5 TiO 3 (BST) film growth by ion sputtering on bare and thermally oxidized silicon was observed in real time using in-situ spectroscopic ellipsometry and time of flight ion scattering and recoil spectrometry techniques. At the outset of BST film deposition on silicon, an approximately 30 Å film with intermediate static dielectric constant (K∼12) and refractive index (n∼2.6 at photon energies of 1.5–3.25 eV) interface layer formed on bare silicon. The interface layer growth rate was greatly reduced on an oxidized silicon substrate. The results have profound implications on the static dielectric constant of BST.