Zinc oxide (ZnO) and aluminum-doped zinc oxide (ZnO:Al) thin films were deposited onto glass and silicon substrates by RF magnetron sputtering using a zinc-aluminum target. Both films were deposited at a growth rate of 12.5 nm/min to a thickness of around 750 nm. In the visible region, the films exhibit optical transmittances which are greater than 80%. The optical energy gap of ZnO films increased from 3.28 eV to 3.36 eV upon doping with Al. This increase is related to the increase in carrier density from 5.9 × 1018 cm-3 to 2.6 × 1019 cm-3. The RMS surface roughness of ZnO films grown on glass increased from 14 to 28 nm even with only 0.9% at Al content. XRD analysis revealed that the ZnO films are polycrystalline with preferential growth parallel to the (002) plane, which corresponds to the wurtzite structure of ZnO.
 K. Ellmer, A. Klein and B. Rech (Eds.), “Transparent Conductive Zinc Oxide: Basics and Applications in Thin Film,” Springer, New York, 2008.
 B. Singh, Z. A. Khan, I. Khan and S. Ghosh, “Highly Conducting Zinc Oxide Thin Films Achieved without Postgrowth Annealing,” Applied Physics Letters, Vol. 97, 2010, Article ID: 241903.
 N. Hasuike, K. Nishio, K. Kisoda, and H. Harima, “Room Temperature Growth of Al-Doped ZnO Thin Films by Reactive DC Sputtering Technique with Metallic Target,” Japanese Journal of Applied Physics, Vol. 52, 2013, Article ID: 01AC09.
 R. Vinodkumar, I. Navas, S. R. Chalana, K. G. Gopchandran, V. Ganesan, R. Philip, S. K. Sudheer and V. P. Mahadevan Pillai, “Highly Conductive and Transparent Laser Ablated Nanostructured Al:ZnO Thin FILMS,” Applied Surface Science, Vol. 257, No. 3, 2010, pp. 708716. http://dx.doi.org/10.1016/j.apsusc.2010.07.044
 S. Nicolay, S. Fay and C. Ballif, “Growth Model of MOCVD Polycrystalline ZnO,” Crystal Growth & Design, Vol. 9, No. 11, 2009, pp. 4957-4962.
 J. J. Robbins, J. Harvey, J. Leaf, C. Fry and C. A. Wolden, “Transport Phenomena in High Performance Nonocrystalline ZnO:Ga Films Deposited by Plasma-Enhanced Chemical Vapor Deposition,” Thin Solid Films, Vol. 473, No. 1, 2005. pp. 35-40.
 S. Chirakkara, K. K. Nanda and S. B. Krupanidhi, “Pulsed Laser Deposited ZnO: In as Transparent Conducting Oxide,” Thin Solid Films, Vol. 519, No. 11, 2011, pp. 3647-3652.
 W. R. Saleh, N. M. Saeed, W. A. Twej and M. Alwan, “Synthesis Sol-Gel Derived Highly Transparent ZnO Thin Films for Optoelectronic Applications,” Advances in Materials Physics and Chemistry, Vol. 2, No. 1, 2012, pp. 11-16. http://dx.doi.org/10.4236/ampc.2012.21002
 B. Godbole, N. Badera, S. Shrivastava, D. Jain and V. Ganesan, “Growth Mechanism of ZnO Films Deposited by Spray Pyrolysis Technique,” Materials Sciences and Applications, Vol. 2, 2011, pp. 643-648.
 Y. Okuhara, T. Kato, H. Matsubara, N. Isu and M. Takata, “Near-Infrared Reflection from Periodically AluminumDoped Zinc Oxide Thin Films,” Thin Solid Films, Vol. 519, 2011, pp. 2280-2286.
 Y. H. Hu, Y. C. Chen, H. J. Xu, H. Gao, W. H. Jiang, F. Hu and Y. X. Wang, “Texture ZnO Thin Films and Their Application as Front Electrode in Solar Cells,” Engineering, Vol. 2, 2010, pp. 973-978.
 P. Genevée, F. Donsantia, G. Renou and D. Lincot, “Study of the Aluminum Doping of Zinc Oxide Films Prepared by Atomic Layer Deposition at Low Temperature,” Applied Surface Science, Vol. 264, 2013, pp. 464469. http://dx.doi.org/10.1016/j.apsusc.2012.10.045
 J. J. Lu, S. Y. Tsai, Y. M. Luc, T. C. Lin and K. J. Gan, “Al-Doping Effect on Structural, Transport and Optical Properties of ZnO Films by Simultaneous RF and DC Magnetron Sputtering,” Solid State Communications, Vol. 149, 2009, pp. 2177-2180.
 S. Cornelius, M. Vinnichenko, N. Shevchenko, A. Rogozin, A. Kolitsch and W. Moller, “Achieving High Free Electron Mobility in ZnO:Al Thin Films Grown by Reactive Pulsed Magnetron Sputtering,” Applied Physics Letters, Vol. 94, No. 4, 2009, Article ID: 042103.
 C. A. Tseng, J. C. Lin, Y. F. Chang, S. D. Chyou and K. C. Peng, “Microstructure and Characterization of AlDoped ZnO Films Prepared by RF Power Sputtering on Al and ZnO Targets,” Applied Surface Science, Vol. 258, No. 16, 2012, pp. 5996-6002.
 A. P. Roth, J. B. Webb and D. F. Willians, “Absorption Edge Shift in ZnO Thin Films at High Carrier Densities,” Solid State Communications, Vol. 39, No. 12, 1981, pp. 1269-1271. http://dx.doi.org/10.1016/0038-1098(81)90224-6
 J. G. Lu, Z. Z. Ye, Y. J. Zeng, L. P. Zhu and L. Wang, “Structural, Optical, and Electrical Properties of (Zn,Al)O Films over a Wide Range of Compositions,” Journal of Applied Physics, Vol. 100, No. 7, 2006, Article ID: 073714. http://dx.doi.org/10.1063/1.2357638
 Y. Kajikawa, “Texture Development of Non-Epitaxial Polycrystalline ZnO Films,” Journal of Crystal Growth, Vol. 289, No. 1, 2006, pp. 387-394.
 Y. Y. Liu, S. Y. Yang, G. X. Wei, H. S. Song, C. F. Cheng, C. S. Xue and Y. Z. Yuan, “Electrical and Optical Properties Dependence on Evolution of Roughness and Thickness of Ga:ZnO Films on Rough Quartz Substrates,” Surface & Coatings Technology, Vol. 205, No. 11, 2011, pp. 3530-3534.
 X. Wang, X. Zeng, D. Huang, X. Zhang and Q. Li, “The Properties of Al Doped ZnO Thin Films Deposited on Various Substrate Materials by RF Magnetron Sputtering,” Journal of Materials Science: Materials in Electronics, Vol. 23, No. 8, 2012, pp. 1580-1586.