ABSTRACT Thin films of Zinc Oxide (ZnO) having different concentrations were deposited using the Aqueous Chemical Growth (ACG) method. The films were characterized using Rutherford Back Scattering (RBS) spectroscopy for chemical composition and thickness, X-Ray Diffraction (XRD) for crystallographic structure, a UV-VIS spectrophotometer for the analysis of the optical and solid state properties which include spectral absorbance, transmittance, reflectance, refractive index, direct band gap, real and imaginary dielectric constants, absorption and extinction coefficients and a photomicroscope for photomicrographs. The average deposited film thickness was 100 nm. The results indicate that the values of all the optical and solid state properties investigated vary directly with concentration except transmittance which is the reverse. Thus, the optical and solid state properties of ZnO thin film deposited by the Acqueous Chemical Growth method can be tuned by deliberately controlling the concentration of the precursors for various optoelectronic applications including its application as absorber layer in solar cells.
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S. Mammah, F. Opara, F. Sigalo, S. Ezugwu and F. Ezema, "Effect of Concentration on the Optical and Solid State Properties of ZnO Thin Films Deposited by Aqueous Chemical Growth (ACG) Method," Journal of Modern Physics, Vol. 3 No. 9, 2012, pp. 947-954. doi: 10.4236/jmp.2012.39124.
 T. Kiyoshi; Y. Akihiko and S. Adarsh “Wide Bandgap Semiconductors: Fundamental Properties and Modern Photonic and Electronic Devices,” Springer, Heidelberg, 2007, p. 257.
 C. Klingshirn, “ZnO: Material, Physics and Applications,” Physical Chemistry, Vol. 8, No. 6, 2007, pp. 782-803.
 E. Wiberg and A. F. Holleman, “Inorganic Chemistry,” Elsevier, Amsterdam, 2001.
 J. W. Nicholson, Journal of Materials Science, Vol. 33, No. 225, 1998.
 J. L. Ferracane, “Material in Dentistry: Principles and Application,” Lippincott Williams & Wilkins, Philadelphia, 2001.
 C. K. Park, M. R. Silsbee and D. M. Roy, “Setting Reaction and Resultant Structure of Zinc Phosphate Cement in Various Orthophosphoric Acid Cement-Forming Liquids,” Cement and Concrete Research, Vol. 28 No. 1, 1998, pp. 141-150. doi:10.1016/S0008-8846(97)00223-8UH
 N. N. Greenwood and A. Earnshaw, “Chemistry of the Elements,” Butterworth-Heinemann, Oxford, 1997.
 U. ?zgür, Y. T. Alivov, C. Liu, A. Teke, M. A. Reshchikov, S. Do?an, V. Avrutin, S. J. Cho, et al., “A Comprehensive Review of ZnO Materials and Devices,” Journal of Applied Physics, Vol. 98, No. 4, 2005, pp. 041401-041502.
 S. Baruah and J. Dutta, “Hydrothermal Growth of ZnO Nanostructures,” Science and Technology of Advanced Materials, Vol. 10, No. 1, 2009, p. 013001.
 U. Rossler, “Landolt-Bornstein, New Series, Group III,” Springer, Heidelberg, 1999.
 T. Mahalingam, V. S. John, M. Raja, Y. K. So and P. J. Sabastian, “Electrodeposition and Characterization of Transparent ZnO Thin Films,” Solar Energy Materials and Solar Cells, Vol. 88, No. 2, 2005, pp. 227-235.
 Y. R. Shinde, T. P. Gujar, C. D. Lokhande, R. S. Nane and S. H. Han, Materials Chemistry and Physics, Vol. 326, 2006.
 A. E. Ajuba, S. C. Ezugwu, P. U. Asogwu and F. I. Ezema, Chalcogenide Letter, Vol. 10, 2010, pp. 573-579.
 T. Soki, Y. Hatanaka and D. C. Look, “ZnO Diode Fabricated by Excimer-Laser Doping,” Applied Physics Letters, Vol. 76, No. 22, 2000, pp. 3257-3259.
 Y. Lin. C. R. Gorla, S. Linng, N. Emanetoglu, Y. Tor, H. Shen and M. Wraback, ‘Ultraviolet Detectors Based on Epitaxial ZnO Films Grown by MOCVD,” Journal of Electronic Materials, Vol. 29, No. 1, 2000, pp. 69-74.
 V. R. Shinde, T. P. Gujar and C. D. Lokhande, “LPG Sensing Properties of ZnO Films Prepared by Spray Pyrolysis Method: Effect of Molarity of Precursor Solution,” Sensors and Actuators H, Vol. 120, No. 2, 2007, pp. 551-559.
 A. Ennaoui, S. Siebentrith, M. Ch. Lux-Steiner, W. Riedl and F. Karg, “High-Efficiency Cd-Free CIGSS Thin-Film Solar Cells with Solution Grown Zinc Compound Buffer Layers,” Solar Energy Materials and Solar Cells, Vol. 67, No. 1-4, 2002, pp. 31-40.
 Y. Chen, D. Bagnall and T. Yao, “ZnO as a Novel Photonic Material for the UV Region,” Materials Science and Engineering B, Vol. 75, No. 2-3, 2000, pp. 190-198.
 S. Liang, H. Sheng, Y. Liu, Z. Hio, Y. Lu and H. Shen, Journal of Crystal Growth, Vol. 225, No. 110, 2001.
 M. H. Koch, P. Y. Timbrell and R. N. Lamb, “The Influence of Film Crystallinity on the Coupling Efficiency of ZnO Optical Modulator Waveguides,” Semiconductor Science and Technology, Vol. 10, No. 11, 1995, p. 1523.
 C. R. Gorla, N. W. Emanetoglu, S. Liang, W. E. Mayo, K. Lu, M. Wraback and H. Shen, “Structural, Optical, and Surface Acoustic Wave Properties of Epitaxial ZnO Films Grown on (012) Sapphire by Metalorganic Chemical Vapor Deposition,” Journal of Applied Physics, Vol. 85, No. 5, 1999, pp. 2595-2603.
 V. R. Shinde, C. D. Lokhande, R. S. Mane and S. H. Han, “Hydrophobic and Textured ZnO Films Deposited by Chemical Bath Deposition: Annealing Effect,” Applied Surface Science, Vol. 245, No. 1-4, 2005, pp. 407-413.
 A. Ennaoui, M. Weber, R. Scheer and H. J. Lewerenz, “Chemical-Bath ZnO Buffer Layer for CuInS2 Thin-Film Solar Cells,” Solar Energy Materials and Solar Cells, Vol. 54, No. 1-4, 1998, pp. 277-286.
 D. S. Boyle, K. Governder and P. O’Brien, Chemical Communications, Vol. 1, No. 80, 2002, p. 23.
 M. Ortega-Lope, A. Avila-Gaecia, M. L. Albor-Aguitera and V. M. Sankez Resendiz, “Improved Efficiency of the Chemical Bath Deposition Method during Growth of ZnO Thin Films,” Materials Research Bulletin, Vol. 38, No. 4, 2003, pp. 1241-1248.
 F. I. Ezema, Journal of Research (Science), Vol. 15, No. 4, 2004, pp. 343-350.
 V. R. Shinde, T. P. Gujar and C. D. Lokhande, “Studies on Growth of ZnO Thin Films by a Novel Chemical Method,” Solar Energy Materials and Solar Cells, Vol. 91, No. 12, 1961, pp. 1055-1061.
 A. Jimenez Gonzalez and R. Suarez-Para, “Effect of Heat Treatment on the Properties of ZnO Thin Films Prepared by Successive Ion Layer Adsorption and Reaction (SIL- AR),” Journal of Crystal Growth, Vol. 167, No. 3-4, 1996, pp. 649-655.
 M. L. de la Olvera, A. Maldonado, R. Asomoza and M. Melendez-Lira, “Effect of the Substrate Temperature and Acidity of the Spray Solution on the Physical Properties of F-Doped ZnO Thin Films Deposited by Chemical Spray,” Solar Energy Materials and Solar Cells, Vol. 71, No. 1, 2002, pp. 61-71.
 P. M. Izaki and T. Omi, Journal of The Electrochemical Society, Vol. 144, 1997, pp. 1949-1952.
 D. Gal, G. Hodes, D. Lincot and H. W. Sechock, “Electrochemical Deposition of Zinc Oxide Films from Non-Aqueous Solution: A New Buffer/Window Process for Thin Film Solar Cells,” Thin Solid Films, Vol. 361-362, 2000, pp. 79-83.
 X. Hu, Y. Masuda, T. Olyi and K. Kato, “Fabrication of ZnO Nanowhiskers Array Film by Forced-Hydrolysis-Initiated-Nucleation Technique Using Various Templates,” Thin Solid Films, Vol. 518, No. 2, 2009, pp. 621-624.
 X. Zhang, L. Wang and G. Zhow, “Synthesis of Well-Aligned ZnO Nanowires without Catalysts,” Reviews on Advanced Materials Science, Vol. 10, 2005, pp. 69-72.
 S.-F. Lee, L.-Y. Lee and Y.-P. Change, Journal of Science and Engineering Technology, Vol. 5, No. 3, 2009, pp. 13-20.
 A. E. Ajuba, S. C. Ezugwu, B. A. Ezekoye, F. I. Ezema and P. U. Asogwa, Journal of Optoelectronics and Biomedical Materials, Vol. 2, No. 2, 2009, pp.73-78.
 V. R. Shinde, C. D. Lokhande, R. S. Mane and S. H. Han, Applied Surface Science, Vol. 245, No. 407, 2005.
 P. Li, H. Liu, F. X. Xu and Y. Wei, “Controllable Growth of ZnO Nanowhiskers by a Simple Solution Route,” Materials Chemistry and Physics, Vol. 112, No. 2, 2008, pp. 393-397.
 H. Zhai, W. Wu, F. Lu and H. S. Wang, “Effects of Ammonia and Cetyltrimethylammonium Bromide (CTAB) on Morphologies of ZnO Nano- and Micromaterials under Solvothermal Process,” Material Chemistry and Physics, Vol. 112, No. 3, 2008, pp. 1024-1028.
 D. Yiamsawas, K. B. Savanitchakul and W. K. W. Supamonkon, Journal of Microscopy Society of Thailand, Vol. 13, No. 75, 2009.
 S. Y. Chu and T. M. Yan, “Characteristics of Sol-Gel Synthesis of ZnO-Based Powders,” Journal of Materials Science Letters, Vol. 19, No. 4, 2000, pp. 349-352.
 D. Geeth and T. Tilagarathi, Digest Journal of Nanomaterials and Biostructures, Vol. 5, No. 1, 2010, p. 297301.
 C. Gumus, O. M. Ozkendir, H. Kavak and Y. Ufuktepe, Journal of Optoelectronics and Advanced Materials, Vol. 8, No. 1, 2006, pp. 299-303.
 C. Cruz-Vázquez, F. Rocha-Alonzo, S. E. Burruel-Ibarra, M. Inoue and R. Bernal, “Fabrication and Characterization of Sulfur Doped Zinc Oxide Thin Films,” Superficies y Vacío, Vol. 13, 2001, pp. 89-91.
 A. Sachez-Juarez, A. Tiburcio-Silver and A. Ortiz, Solar energy Materials and Solar Cells, Vol. 52, No. 3-4, 1998, pp. 301-311. HUdoi:10.1016/S0927-0248(97)00246-8U
 P. Pushparajah, A. K. Arof and S. Radhakrishna, “Physical Properties of Spray Pyrolysed Pure and Doped ZnO Thin Films,” Journal of Physics D: Applied Physics, Vol. 27, No. 7, 1994, pp. 1518-1521.
 A. E. Jimenez Gonzalex and J. A. Soto Urueta, “Optical Transmittance and Photoconductivity Studies on ZnO:Al Thin Films Prepared by the Sol-Gel Technique,” Solar Energy Materials and Solar Cells, Vol. 52, No. 3-4, 1998, pp. 345-353. HUdoi:10.1016/S0927-0248(97)00243-2U
 L. Vayssieres, “On the Design of Advanced Metal Oxide Nanomaterials,” International Journal of Nanotechnology, Vol. 1, No. 1-2, 2004, pp. 1-41.