Nanoplatform based on ideally ordered arrays of short straight and long beer bottle-shaped nanochannels

Abstract A combination of focused ion beam lithography and a two-step anodization process has been used to fabricate an ideally long-range ordered nanoplatform containing short straight and long beer bottle-shaped nanochannels. The lithography is performed by direct ion irradiation to pattern an electro-polished aluminium sheet with a custom-designed array of nanoholes. The ion irradiation time for some selected nanoholes are longer than that for the others. All the nanoholes form an ideally ordered two-dimensional hexagonally close-packed structure while those caused by the longer irradiation show a similar arrangement with a double periodicity. All the holes guide the growth of alumina nanochannels in the first anodization step under a specific anodization voltage. The second step under a twice reaction voltage forces the inter-nanochannel distance to increase by twice and thus terminates the growth of many nanochannels. All the terminated nanochannels are related to the lower ion-irradiation, since unfavoured in the growth competition during the second step anodization. The size of survived nanochannels increases by twice in this step because of the enhanced voltage. Finally, nanochannels corresponding to lower and higher irradiations evolve into short straight and long beer bottle-shaped nanochannels respectively. The mechanism behind nanochannel growth and possible application of such custom-designed nanoplatforms are discussed.