Nanowire Fabrication Based on Porous Alumina TemplatePorous oxide – unique for AlElectrochemical mechanismRegular hole array – top viewIdeally Ordered Anodic Porous Alumina Using Pretextured AlIdeally Ordered Anodic Porous AluminaMetal nanowire growthFabrication processesSlide 9Nanowire growthSelective area growthSemiconductor nanowiresFabrication of carbon nanotubesMetal Nanodot ArraysSlide 15Nanowire Fabrication Based on Porous Alumina TemplateEE235 NanofabricationJie YaoApril 09, 2007Porous oxide – unique for Al•Al can be anodized into porous oxide,which is an unique property of aluminumSchematic of the anodic porous aluminum oxide layerSEM images of the porous alumina layerElectrochemical mechanism•The overall reaction that takes place during anodization is: 2Al + 3H2O => Al2O3 + 3H2 At the anode: 2Al + 3O2- => Al2O3 + 6e- At the cathode:6H+ + 6e- ==> 3H2 •The Al is oxidized at the metal/oxide interface•The oxide is etched away by the acid with the applied potential•The pores are induced by the roughness of the top surfaceTEM micrographsRegular hole array – top view•The mechanism determines that the holes can form regular arrays: The distance between the holes tends to be uniform•Type of acid, concentration, temperature and applied voltage are the major factors that affects the porous structureSEM images of the regular hole arrays with different hole diameters (top view)Ideally Ordered Anodic PorousAlumina Using Pretextured Al•H. Asoh, K. Nishio, M. Nakao, T. Tamamura, and H. Masuda, Journal of The Electrochemical Society Vol. 148 SiC mold used to make the perfect array on AlIdeally ordered hole arraysIdeally Ordered Anodic PorousAlumina•Both the texture and the reaction mechanism determines the pore array formationSide viewMetal nanowire growth•Metal nanowires, such as silver, gold, nickel, can be fabricated in the template using electroplating methodSEM images showing nanowires grown inside the porous templateFabrication processesAluminumBarrier layerTemplateIn a plastic basketHgCl2Rinse with deionized water•Removal of aluminum•Handling with glass slideFabrication processes•Seed layer depositionSilverGlass slideNanowire growth•Barrier layer removal•Nanowire depositionH3PO4Cu platePt anodeAg+Selective area growth M.A.S.Chong et al, Appl.Phys.Lett. (2006)Semiconductor nanowiresZ. Fan et al, Appl. Phys. Lett. (2006)Fabrication of carbon nanotubes•The films were impregnated under vacuum with a mixture of furfuryl alcohol and oxalic acid•Polymerization and carbonizationT Kyotani et al, Chem. Mater. 1996Metal Nanodot ArraysS.K.Park et al, Cur.Appl.Phys. (2007)Au, Al, Ag, Cu, Pb, Sn, and Zn nanodots have been madeMelting point determines the way of depositionThank
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