Synthesis and Characterization of Co₃O₄ Thin Film

Vikas Patil, Pradeep Joshi, Manik Chougule, Shashwati Sen

.

DOI: 10.4236/snl.2012.21001                

Abstract

Nanosized Co₃O₄ thin films were prepared on glass substrates by using sol-gel spin coating technique. The effect of annealing temperature (400°C - 700°C) on structural, morphological, electrical and optical properties of Co₃O₄ thin films were studied by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Electrical conductivity and UV-visible Spectroscopy (UV-Vis). XRD measurements show that all the films are nanocrystallized in the cubic spinel structure and present a random orientation. Six prominent peaks, corresponding to the (111) phase (2θ ≈ 18.90°), (220) phase (2θ ≈ 31.29°), (311) phase (2θ ≈ 36.81°), (222) phase (2θ ≈ 38.54°), (400) phase (2θ ≈ 44.80°), (511) phase (2θ ≈ 59.37°) and (440) phase (2θ ≈ 65.27°) appear on the diffractograms. The crystallite size increases with increasing annealing temperature. These modifications influence the optical properties. The morphology of the sol gel derived Co₃O₄ shows nanocrystalline grains with some overgrown clusters and it varies with annealing temperature. The optical band gap has been determined from the absorption coefficient. We found that the optical band gap energy decreases from 2.58 eV to 2.07 eV with increasing annealing temperature between 400°C - 700°C. These mean that the optical quality of Co₃O₄ films is improved by annealing. The dc electrical conductivity of Co₃O₄ thin films were increased from 10^–4 to 10^–2 (Ω^.cm)^–1 with increase in annealing temperature. The electron carrier concentration (n) and mobility (μ) of Co₃O₄ films annealed at 400°C - 700°C were estimated to be of the order of 2.4 to 4.5 × 10¹⁹ cm^–3 and 5.2 to 7.0 × 10^–5 cm^2.V^–1.s^–1 respectively. It is observed that Co₃O₄ thin film annealing at 700°C after deposition provide a smooth and flat texture suited for optoelectronic applications.

Keywords

Sol Gel Method; Structural Properties; Optical Properties; Electrical Properties

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	A. O. Gulino, P. Dapporto, P. Rossi and I. Fragalà, “Novel Self-Generating Liquid MOCVD Precursor for Co3O4 Thin Films,” Chemistry of Materials, Vol. 15, No. 20, 2003, pp. 3748-3752. doi:10.1021/cm034305z
[2]	S. G. Kandalkar, C. D. Lokhande, R. S. Mane and S. H. Han, “Preparation of Cobalt Oxide Thin Films and Its Use in Supercapacitor Application,” Applied Surface Sci- ence, Vol. 254, No. 17, 2008, pp. 5540-5544. doi:10.1016/j.apsusc.2008.02.163
[3]	Y. Chen, Y. Zhang and S. Fu, “Synthesis and Characterization of Co3O4 Hollow Spheres,” Materials Letters, Vol. 61, No. 3, 2007, pp. 701-705. doi:10.1016/j.matlet.2006.05.046
[4]	Y. Dong, K. He, L. Yin and A. Zhang, “A Facile Route to Controlled Synthesis of Co3O4 Nanoparticles and Their Environmental Catalytic Properties,” Nanotechnology, Vol. 18, No. 43, 2007, pp. 435602-435608. doi:10.1088/0957-4484/18/43/435602
[5]	X. W. Lou, D. Deng. J. Y. Lee, J. Feng and L. A. Archer, “Self-Supported Formation of Needlelike Co3O4 Nanotubes and Their Application as Lithium-Ion Batteries Electrodes,” Advanced Materials, Vol. 20, No. 2, 2008, pp. 258-262.
[6]	S. Lian, E. Wang, L. Gao and L. Xu, “Fabrication of Single-Crystalline Co3O4 Nanorods via a Low-Temperature Solvothermal Process,” Materials Letters, Vol. 61, No. 18, 2007, pp. 3893-3896. doi:10.1016/j.matlet.2006.12.052
[7]	D. Zou, C. Xu, H. Luo, L. Wang and T. I. Ying, “Synthesis of Co3O4 Nanoparticles via an Ionic Liquid-Assisted Methodology at Room Temperature,” Materials Letters, Vol. 62, Vol. 12-13, 2008, pp. 1976-1978.
[8]	P. Poizot, S. Laruelle, S. Grugeon, L. Dupont and J. M. Tarascon, “Nano-Sized Transition-Metal Oxides as Negative-Electrode Materials for Lithium-Ion Batteries,” Nature, Vol. 407, No. 6803, 2000, pp. 496-499.
[9]	B. Varghese, T. C. Hoong, Y. W. Zhu, M. V. Reddy, V. R. Chowdari, T. S. Wee, B. C. Vincent, C. T. Lim and C. Sow, “Co3O4 Nanostructures with Different Morphologies and Their Field-Emission Properties,” General & Introductory Materials Science, Vol. 17, No. 12, 2007, pp. 1932-1939. doi:10.1002/adfm.200700038
[10]	J. Jiang, L.-C. Li, “Synthesis of Sphere-Like Co3O4 Nan- ocrystals via a Simple Polyol Route,” Materials Letters, Vol. 61, No. 27, 2007, pp. 4894-4896. doi:10.1016/j.matlet.2007.03.067
[11]	J. Gao, Y. Zhao, W. Yang, J. Tian, F. Guan and Y. Ma, “Sol Gel Synthesis of Co3O4,” Journal of University of Science and Technology Beijing, Vol. 10, No. 1, 2003, pp. 54-57.
[12]	H. Shim, V. R. Shinde, H. Kim, Y. Sung and W. Kim, “Porous Cobalt Oxide Thin Films from Low Temperature Solution Phase Synthesis for Electrochromic Electrode,” Thin Solid Films, Vol. 516, No. 23, pp. 8573-8578. doi:10.1016/j.tsf.2008.05.055
[13]	L. Pan and Z. Zhang “Prepartion, Electrocatalytic and Pho- tocatalytic Performances of Nanoscised CuO/ Co3O4 Com- posite Oxides,” Journal of Materials Science: Materials in Electronics, Vol. 21, No. 12, 2010. pp. 1262-1269. doi:10.1007/s10854-010-0059-1
[14]	V. Gupta and A. Mansingh, “Influence of Post-Deposi- tion Annealing on the Structural and Optical Properties of Sputtered Zinc Oxide Film,” Journal of Applied Physics, Vol. 80, No. 2, 1996, pp. 1063-1073. doi:10.1063/1.362842
[15]	T. P. Gujar, V. R. Shinde, C. D. Lokhande, R. S. Mane and S.-H. Han, “Bismuth Oxide Thin Films Prepared by Chemical Bath Deposition (CBD) Method: Annealing Effect,” Applied Surface Science, Vol. 250, No. 1-4, 2005, pp. 161-167. doi:10.1016/j.apsusc.2004.12.050
[16]	S. G. Pawar, S. L. Patil, M. A. Chougule and V. B. Patil, “Synthesis and Characterization of Nanocrystalline TiO2 Thin Films,” Journal of Materials Science: Materials in Electronics, Vol. 22, No. 3, 2011, pp. 260-264. doi:10.1007/s10854-010-0125-8
[17]	R. R. Heikes and R. W. Ure, “Thermoelectricity Science and Engineering,” lnster Science, New York, 1961.
[18]	V. B. Patil, S. G. Pawar, S. L. Patil, “ZnO Nanocrystalline Thin Films: A Correlation of Microstructural, Optoelectronic Properties,” Journal of Materials Science: Materials in Electronics, Vol. 21, No. 4, 2010, pp. 355-359. doi:10.1007/s10854-009-9920-5
[19]	R. L. Petriz, “Barrier Theory of the Photoconductivity of Lead Sulfide,” Physical Review, Vol. 104, 1956, pp. 1508- 1516.
[20]	G. Micocci, A. Tepore, R. Rella and O. P. Sicilian, “Electrical and Optical Characterization of Electron Beam Evaporated In2Se3 Thin Films,” Physica Status Solidi (a), Vol. 148, No. 2, 1995, pp. 431-438. doi:10.1002/pssa.2211480211
[21]	F. B. Michehti and P. Mark, “Effect of Chemisorbed Oxygen on the Electrical Properties of Chemically Sprayed CdS Thin Films,” Applied Physics Letters, Vol. 10, No. 4, 1967, pp. 136-140. doi:10.1063/1.1754881
[22]	P. S. Patil, L. D. Kadam, C. D. Lokhande, “Preparation and Characterization of Spray Pyrolysed Cobalt Oxide Thin Films,” Thin Solid Films, Vol. 272, No. 1, 1996, pp. 29-32. doi:10.1016/0040-6090(95)06907-0
[23]	S. G. Khandalkar, J. L. Gunjalkar, C. D. Lokhande and O.-S. Joo, “Synthesis of Cobalt Oxide Interconnected Flackes and Nano-Worms Structures Using Low Temperature Chemical Bath Deposition,” Journal of Alloys and Compounds, Vol. 478, No. 1-2, 2009, pp. 594-598. doi:10.1016/j.jallcom.2008.11.095
[24]	J. H. Lee, K. H. Ko and B. O. Park, “Electrical and Optical Properties of ZnO Transparent Conducting Films by the Sol-Gel Method,” Journal of Crystal Growth, Vol. 247, No. 1-2, 2003, pp. 119-125. doi:10.1016/S0022-0248(02)01907-3
[25]	R.-J. Hong, J.-B. Huang, H.-B. He, Z.-X. Fan and J.-D. Shao “Influence of Different Post-Treatments on the Stru- cture and Optical Properties of Zinc Oxide Thin Films,” Applied Surface Science, Vol. 242, No. 3-4, 2005, pp. 346-352. doi:10.1016/j.apsusc.2004.08.037
[26]	A. M. Chaparro, M. A. Martinez, C. Guillen, R. Bayon, M. T. Gutierrez and J. Herrero, “SnO2 Substrate Effects on the Morphology and Composition of Chemical Bath Deposited ZnSe Thin Films,” Thin Solid Films, Vol. 361-362, No. 1-2, 2000, pp. 177-182. doi:10.1016/S0040-6090(99)00791-9
[27]	D.-H. Bao, X. Yao, N. Wakiya, K. Shinozaki and N. Mizutani, “Band-Gap Energies of Sol-Gel-Derived SrTiO3 Thin Films,” Applied Physics Letters, Vol. 79, No. 23, 2001, pp. 3767-3772. doi:10.1063/1.1423788