Growth and characterization of Ba(Cd _1/3Ta _2/3)O ₃ thin films

We have synthesized stoichiometric Ba(Cd _1/3Ta _2/3)O ₃ [BCT] (100) dielectric thin films on MgO (100) substrates using Pulsed Laser Deposition. Over 99% of the BCT film was found to be epitaxial [BCT (100) || MgO (100) and BCT (010) || MgO (010)] when grown with an elevated substrate temperature of 635°C, an enhanced oxygen pressure of 53 Pa and a Cd-enriched BCT target with a 1 mol BCT: 1.5 mol CdO composition. A dielectric constant of 32 was inferred from low-frequency capacitance measurements of a planar interdigital metal pattern. Analysis of ultra violet optical absorption results indicates that BCT has a bandgap of 4.9 eV; while the interference pattern in the visible range is consistent with a refractive index of 2.1. Temperature-dependent electrical measurements indicate that the BCT films have a room temperature conductivity of 3 × 10 ^{- 12} Ω ^{- 1} cm ^{- 1} with a thermal activation energy of 0.7 eV. A mean particle size of ∼ 100 nm and a root mean square surface roughness of 5 to 6 nm were measured using Atomic Force Microscopy.