Role of solution pH on the microstructural properties of spin coated cobalt oxide thin films

S. Valanarasu, V. Dhanasekaran, M. Karunakaran, R. Chandramohan, T. Mahalingam

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Cobalt Oxide (Co3O4) thin films have been successfully coated onto glass substrates at various solution pH by sol-gel spin coating technique. The film thickness was estimated using weight gain method and it revealed that the film thickness increased with solution pH values. The prepared film structural, morphological, optical and electrical properties were studied using X-ray diffraction (XRD), scanning electron microscope (SEM), UV-Vis-NIR spectrophotometer and Vander Pau method, respectively. The structure of the films were found to be face centered cubic with preferential orientation along (311) plane. X-ray line profile analysis was used to evaluate the micro structural parameters such as crystallite size, micro strain, dislocation density and stacking fault probability. The crystallite size values are increased with increase of solution pH values and maximum value of crystallite is estimated at 40.8 nm at solution pH 8 ± 0.1. Morphological results showed that the pH of the solution has a marked effect on morphology of the Co3O4 thin films. The optical studies revealed that the band gap can be tailored between 2.16 to 2.31 eV by altering pH. The thin film formed at a solution pH 7 is found to have a low resistivity and high mobility. The electrical resistivity (ρ), carrier concentration (n) and mobility (μ) values are 0.1 × 103 Ω cm, 8.9 cm2 γs-1 and 6.6 × 1014 crrr3, respectively for Co3O4 thin film prepared at solution pH 7 ± 0.1. EDAX studies showed that the cobalt content increased and the oxygen content decreased with increase of pH.

Original languageEnglish
Pages (from-to)4286-4291
Number of pages6
JournalJournal of Nanoscience and Nanotechnology
Volume14
Issue number6
DOIs
StatePublished - Jun 2014

Keywords

  • Cobalt oxide
  • Electrical properties
  • Morphological studies
  • Optical properties
  • Structural studies
  • Thin films

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