resumo
Thin films of (Ba-0.5, Sr-0.5) TiO3 (BST5) were deposited at ambient temperature on fused silica substrates by RF magnetron sputtering technique. Nano-crystalline films were obtained upon quasi-rapid thermal annealing (Q-RTA) at temperatures >= 800 degrees C for 60 s. The influence of Q-RTA temperature on the structural, morphological, optical and microwave dielectric properties of BST5 thin films have been investigated. The as-deposited and Q-RTA films annealed up to 700 degrees C were amorphous in nature. On increasing the Q-RTA temperature to 800 degrees C and above resulted in an amorphous-crystalline phase transition in the films. All the crystalline films show similar full width at half maxima (FWHM) and hence, similar crystallite size of about 12 +/- 1 nm. The amorphous-crystalline transition was accompanied by a decrease in the optical band gap from 4.5 to 3.6 and increase in the refractive index from 1.9 to 2.2 as well as in the microwave dielectric constant from 40 to 262. The Root Mean Square roughness (RMSroughness) as measured from AFM show an increase from 0.6 nm to 5.6 nm with an increase in Q-RTA temperature from 400 degrees C to 1000 degrees C. (C) 2013 Elsevier B.V. All rights reserved.
palavras-chave
MICROWAVE DIELECTRIC-PROPERTIES; WAVE-GUIDE; PERMITTIVITY MEASUREMENTS; OPTICAL PROPERTIES; THICKNESS; FABRICATION; RESONATOR; CONSTANTS; ELECTRODE
categoria
Chemistry; Materials Science; Metallurgy & Metallurgical Engineering
autores
Saravanan, KV; Raju, KCJ
nossos autores
Venket
Bolseiro de pós-DoutoramentoGrupos
agradecimentos
The authors acknowledge the financial support from ACRHEM and NPSM. Facilities provided by Department of Science and Technology, India and University Grants Commission, India are gratefully acknowledged. KVS acknowledge FCT, Portugal for the post doctoral grant # SFRH/BPD/80742/2011.