Photoenhanced chemical-vapor deposition of BaTiO₃

Abstract

High quality BaTiO₃ films have been deposited on MgO (100) and Pt coated Si (Pt/Ta/ONO/Si) substrates at 600° C by photoenhanced chemical-vapor deposition (photo-CVD). X-ray-diffraction measurements show that highly a-axis oriented BaTiO₃ was formed on MgO (100) substrates at 600° C by photo-CVD. BaTiO3 films deposited on Pt coated Si substrates by photo-CVD were randomly oriented. In contrast, the x-ray-diffraction peaks of the BaTiO₃ films deposited at the same temperature without UV light irradiation were much weaker than those with UV light irradiation. Raman-scattering measurements showed a pronounced peak at 522 cm^-1, which is characteristic peak of perovskite BaTiO₃, for photo-CVD deposited films. The dielectric constant of photo-CVD deposited BaTiO₃ films (ε=580) was more than double than that of thermal CVD deposited films, while the dissipation factor (loss) of photo-CVD deposited BaTiO₃ films was reduced by a factor of 2. These results unambiguously demonstrated that photo-CVD is a promising technique for low-temperature deposition of high quality ferroelectric films.