Growth and characterization of Ba(Cd1/3Ta2/3)O3 thin films

• Published in: Thin solid films 2012-07, Vol.520 (19), p.6153-6157
• Main Authors: Liu, L.T., Kopas, C., Singh, R.K., Hanley, R.M., Newman, N.
• Format: Article
• Language: English
• Subjects: Ba(Cd1/3Ta2/3)O3; Ba(Zn1/3Ta2/3)O3; Cadmium; Capacitance; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Dielectric thin films; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Electrical measurement; Elevated; Epitaxial growth; Exact sciences and technology; Laser deposition; Magnesium oxide; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Microwave dielectrics; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Optical/electrical properties; Perovskite; Physics; Pulsed Laser Deposition; Resistivity; Theory and models of film growth; Thin films
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2012.06.034

We have synthesized stoichiometric Ba(Cd1/3Ta2/3)O3 [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 53Pa and a Cd-enriched BCT target with a 1mol BCT: 1.5mol 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 4.9eV; 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 3×10−12Ω−1cm−1 with a thermal activation energy of 0.7eV. A mean particle size of ~100nm and a root mean square surface roughness of 5 to 6nm were measured using Atomic Force Microscopy. ► Stoichiometric and epitaxial Ba(Cd1/3Ta2/3)O3 (BCT) thin films were grown. ► Cd enriched targets and higher substrate temperature achieve high quality BCT films. ► Structural, optical and electrical properties of BCT thin films were characterized. ► The bandgap of BCT was determined based on optical measurement.