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Research Letters in Materials Science
Volume 2007, Article ID 95307, 5 pages
http://dx.doi.org/10.1155/2007/95307
Research Letter

Effect of Postdeposition Annealing on the Structural, Electrical, and Optical Properties of DC Magnetron Sputtered Ta2O5 Films

1Department of Physics, Sri Venkateswara University, Tirupati 517502, India
2Department of Instrumentation, Indian Institute of Science, Bangalore 560012, India

Received 12 August 2007; Accepted 5 November 2007

Academic Editor: Maria Antonietta Loi

Copyright © 2007 S. V. Jagadeesh Chandra et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Thin films of tantalum oxide were formed on quartz and silicon (111) substrates kept at room temperature (303 K) by reactive sputtering of tantalum target in the presence of mixture of oxygen and argon gases. The as-deposited films were annealed in air for an hour in the temperature range 673–873 K. The films were characterized by studying structural, dielectric, electrical, and optical properties. The as-deposited films were amorphous in nature. As the annealing temperature increased to 673 K, the films were transformed into polycrystalline. Electrical characteristics of as-deposited and annealed Ta2O5 thin films were compared. The thermal annealing reduced the leakage current density and increased the dielectric constant. The optical transmittance of the films increased with the increase of annealing temperature. The as-deposited films showed the optical band gap of 4.38 eV. It increased to 4.44 eV with the increase of annealing temperature to 873 K. The as-deposited films showed the low value (1.89) of refractive index and it increased to 2.15 when annealed at 873 K. The increase of refractive index with annealing temperature was due to the increase in the packing density and crystallinity of the films.