A multi-electrolyte-step (MES) anodic aluminum oxide (AAO) method was used to achieve nanochannel arrays with good circularity and periodic structure. The nano-channel array fabrication process included immersion in a phosphoric acid solution with a 120–150 bias voltage. Bowl-shaped structures were then formed by removing the walls of the nano-channel arrays. The nano-channel arrays were grown from the bottom of the bowl structure in an oxalic solution using a 50？V bias voltage. A comparison of this new MES process with the one-step and five-step AAO process showed a 50% improvement in the circularity over the one-step process. The standard deviation of the average period in the MES array was 25？nm which is less than that of one-step process. This MES method also took 1/4 of the growing time of the five-step process. The orderliness of the nano-channel arrays for the five-step and MES process was similar. Finally, Cu nanoparticle arrays with a 200？nm period were grown using an electroplating process inside the MES nano-channel arrays on fluorine doped tin oxide glass. Stronger surface plasmon resonance absorption from 550？nm to 750？nm was achieved with the MES process than was possible with the one-step process. 1. Introduction In recent years, surface plasmon resonance (SPR) in nanoparticle array has attracted a lot of attention because of the adjustable absorption band [1, 2]. SPR assisted energy conversion in dye-sensitized solar cell has also been studied [3]. The SPR effect is dependent on the shape and the arrangement of the nanoparticles but it is not easy to achieve good circularity and periodicity in metallic nanoparticle arrays. It has been shown that carbon nanotubes, nanoparticles, quantum dots, and nanopillars can be grown in nanochannel arrays utilizing various methods for their fabrication [4]. The use of the anodic aluminum oxide (AAO) method for the fabrication of nanochannel arrays to nanoparticle arrays has matured [5]. However, the positioning of the nanochannel arrays grown using the AAO method is random making it very difficult to control the hole quality and to form orderly arrays. There have been some methods for growing good quality AAO nanochannel arrays developed. They require either an increase in circularity or improvement in the period of the channels, so it becomes a long process [6]. For example, in the multistep AAO process [7], channels are repeatedly grown and removed to achieve periodic arrays. The problem is the thickness of the raw material, Al, has to be greater than 1？μm, which is too thick for the deposition of a
References
[1]
S. Linic, P. Christopher, and D. B. Ingram, “Plasmonic-metal nanostructures for efficient conversion of solar to chemical energy,” Nature Materials, vol. 10, no. 12, pp. 911–921, 2011.
[2]
J. F. Sanchez-Ramírez, “Preparation and optical absorption of colloidal dispersion of Au/Cu nanoparticles,” Superficies Y Vacio, vol. 15, pp. 16–18, 2002.
[3]
B. Ding, B. J. Lee, M. Yang, H. S. Jung, and J. K. Lee, “Surface-Plasmon Assisted Energy Conversion in Dye-Sensitized Solar Cells,” Advanced Energy Materials, vol. 1, no. 3, pp. 415–421, 2011.
[4]
R.-L. Zong, J. Zhou, B. Li, M. Fu, S.-K. Shi, and L.-T. Li, “Optical properties of transparent copper nanorod and nanowire arrays embedded in anodic alumina oxide,” Journal of Chemical Physics, vol. 123, no. 9, Article ID 094710, 2005.
[5]
Y. Zhang, W. Xu, S. Xu, G. Fei, Y. Xiao, and J. Hu, “Optical properties of Ni and Cu nanowire arrays and Ni/Cu superlattice nanowire arrays,” Nanoscale Research Letters, vol. 7, no. 1, p. 569, 2012.
[6]
C.-K. Chung, T. Y. Liu, and W. T. Chang, “Effect of oxalic acid concentration on the formation of anodic aluminum oxide using pulse anodization at room temperature,” Microsystem Technologies, vol. 16, no. 8-9, pp. 1451–1456, 2010.
[7]
C. Y. Han, G. A. Willing, Z. Xiao, and H. H. Wang, “Control of the anodic aluminum oxide barrier layer opening process by wet chemical etching,” Langmuir, vol. 23, no. 3, pp. 1564–1568, 2007.
[8]
Y. Jia, H. Zhou, P. Luo, S. Luo, J. Chen, and Y. Kuang, “Preparation and characteristics of well-aligned macroporous films on aluminum by high voltage anodization in mixed acid,” Surface and Coatings Technology, vol. 201, no. 3-4, pp. 513–518, 2006.
[9]
S. Shingubara, K. Morimoto, H. Sakaue, and T. Takahagi, “Self-organization of a porous alumina nanohole array using a sulfuric/oxalic acid mixture as electrolyte,” Electrochemical and Solid-State Letters, vol. 7, no. 3, pp. E15–E17, 2004.
[10]
C. Y. Liu, A. Datta, and Y. L. Wang, “Ordered anodic alumina nanochannels on focused-ion-beam-prepatterned aluminum surfaces,” Applied Physics Letters, vol. 78, no. 1, pp. 120–122, 2001.
[11]
S. Shingubara, Y. Murakami, K. Morimoto, and T. Takahagi, “Formation of aluminum nanodot array by combination of nanoindentation and anodic oxidation of aluminum,” Surface Science, vol. 532–535, pp. 317–323, 2003.
[12]
S. H. Chan, C. K. Chen, S. Z. Tseng, C. H. Hsu, and W. H. Cho, “Atomic layer deposition of aluminum-doped zinc oxide films for the light harvesting enhancement of a nanostructured silicon solar cell,” The Journal of Vacuum Science and Technology A, vol. 31, no. 1, pp. 01A125–01A128, 2013.
[13]
C. K. Chen, Y. C. Huang, C. C. Lee, and S. H. Chen, “Omni-directional reflectors for UV LED using symmetric autocloning method,” Optical Review, vol. 20, no. 2, pp. 141–144, 2013.
[14]
I. Cavarretta, C. O'Sullivan, and M. R. Coop, “Applying 2D shape analysis techniques to granular materials with 3D particle geometries,” in Proceedings of the 6th International Conference on Micromechanics of Granular Media, Powders and Grains 2009, pp. 833–836, July 2009.
[15]
A. P. Z. Stevenson, D. B. Bea, S. Civit, S. A. Contera, A. I. Cerveto, and S. Trigueros, “Three strategies to stabilise nearly monodispersed silver nanoparticles in aqueous solution,” Nanoscale Research Letters, vol. 7, pp. 151–158, 2012.
[16]
O. Sanz, F. J. Echave, J. A. Odriozola, and M. Montes, “Aluminum anodization in oxalic acid: controlling the texture of Al2O3/Al monoliths for catalytic aplications,” Industrial and Engineering Chemistry Research, vol. 50, no. 4, pp. 2117–2125, 2011.
[17]
A. Belwalkar, E. Grasing, W. Van Geertruyden, Z. Huang, and W. Z. Misiolek, “Effect of processing parameters on pore structure and thickness of anodic aluminum oxide (AAO) tubular membranes,” Journal of Membrane Science, vol. 319, no. 1-2, pp. 192–198, 2008.
[18]
K. Ersching, E. Dorico, R. C. da Silva et al., “Surface and interface characterization of nanoporous alumina templates produced in oxalic acid and submitted to etching procedures,” Materials Chemistry and Physics, vol. 137, pp. 140–146, 2012.
[19]
A. P. Li, F. Muller, A. Birner, K. Nielsch, and U. Gosele, “Fabrication and microstructuring of hexagonally ordered two-dimensional nanopore arrays in anodic alumina,” Advanced Materials, vol. 11, no. 6, pp. 483–487, 1999.
[20]
H. Masuda, H. Yamada, M. Satoh, H. Asoh, M. Nakao, and T. Tamamura, “Highly ordered nanochannel-array architecture in anodic alumina,” Applied Physics Letters, vol. 71, no. 19, pp. 10–12, 1997.
[21]
A. P. Li, F. Müller, and U. G？sele, “Polycrystalline and monocrystalline pore arrays with large interpore distance in anodic alumina,” Electrochemical and Solid-State Letters, vol. 3, no. 3, pp. 131–134, 2000.
[22]
B. Yu, Y. Gao, and H. Li, “Fabrication and optical characterization of poly(2,5-di-n-butoxyphenylene) nanofibril arrays,” Journal of Applied Polymer Science, vol. 91, no. 1, pp. 425–430, 2004.
[23]
K.-L. Lai, M.-H. Hon, and I.-C. Leu, “Fabrication of ordered nanoporous anodic alumina prepatterned by mold-assisted chemical etching,” Nanoscale Research Letters, vol. 6, pp. 157–162, 2011.
[24]
A. Nourmohammadi, S. J. Asadabadi, M. H. Yousefi, and M. Ghasemzadeh, “Photoluminescence mission of nanoporous anodic aluminum oxide films prepared in phosphoric acid,” Nanoscale Research Letters, vol. 7, pp. 689–695, 2012.
[25]
C.-G. Kuo and C.-C. Chen, “Technique for self-assembly of tin nano-particles on anodic aluminum oxide (AAO) templates,” Materials Transactions, vol. 50, no. 5, pp. 1102–1104, 2009.
[26]
W. Chen, J.-S. Wu, and X.-H. Xia, “Porous anodic alumina with continuously manipulated pore/cell size,” ACS Nano, vol. 2, no. 5, pp. 959–965, 2008.
[27]
L. Zaraska, G. D. Sulka, and M. Jaskua, “Properties of nanostructures obtained by anodization of aluminum in phosphoric acid at moderate potentials,” Journal of Physics: Conference Series, vol. 146, Article ID 012020, pp. 012020–012026, 2009.
[28]
V. P. Parkhutik and V. I. Shershulsky, “Theoretical modelling of porous oxide growth on aluminum,” Journal of Physics D, vol. 25, pp. 1258–1263, 1992.
[29]
J. E. Houser and K. R. Hebert, “Modeling the potential distribution in porous anodic alumina films during steady-state growth,” Journal of the Electrochemical Society, vol. 153, no. 12, Article ID 078612JES, pp. B566–B573, 2006.
[30]
H. Chen, D. S. Chan, C. K. Chen, T. H. Chang, Y. H. Lai, and C. C. Lee, “Nanoimprinting pre-patterned effects on anodic aluminum oxide,” Japanese Journal of Applied Physics, vol. 49, no. 1, pp. 015201–015204, 2010.
