Controlled fabrication of patterned lateral porous alumina membranes

Abstract

Confined lateral alumina templates are fabricated with different pore sizes by changing the acid electrolyte and the anodization voltage. The control of the number of pore rows down to one dimension is also achieved, by controlling the thickness of the starting aluminum film as well as the anodization voltage. We observe that the mechanism of pore formation in the lateral regime is very similar to that in the classical vertical situation.

Fabrication of hexagonally ordered nanopores in anodic alumina: An alternative pretreatment

“…It is to be noted that chemical polishing is much more convenient than electropolishing especially when lateral anodization of aluminum substrate is required. This type of anodization has recently attracted significant attention since it opens the possibility of synthesizing three terminal devices using AAO technique [40,41].…”

Mechanical constraint and release generates long, ordered horizontal pores in anodic alumina templates

“…Recently, other groups have realised similar horizontally-oriented nanochannels following this idea. [16][17][18][19] In these reports, an aluminium film deposited onto an oxidised silicon substrate was etched in parallel strips and then capped with a silicon oxide layer. [16][17][18][19] The short edges of the strips were dipped into the electrolyte and the anodisation proceeded along their lengths.…”

“…[16][17][18][19] In these reports, an aluminium film deposited onto an oxidised silicon substrate was etched in parallel strips and then capped with a silicon oxide layer. [16][17][18][19] The short edges of the strips were dipped into the electrolyte and the anodisation proceeded along their lengths. Cojocaru and coworkers [17] have shown scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of horizontal pores, 200-300 nm long, with pore diameters between 3-4 nm.…”

“…Xiang and co-workers [16] reported the fabrication of horizontal porous templates with controlled pore diameters between 10-130 nm and interpore distances ranging from 30-275 nm, and described a transition from a hexagonal to a square arrangement in the pore ordering when the interpore distance increased to about one quarter of the 225 nm film thickness. Gowtham et al [18] reported the fabrication of arrays of in-plane nanopores within patterned Al fingers wedged between SiO2 layers with a mean pore diameter of 20 nm.…”

“…Gowtham et al include an image of a 'front on' section exposed by a focused ion beam along the anodised Al finger length. [18] The distance of this section from the edge was not defined, and since the image shown was not related to any image at the surface, no 3D information was provided from this section. Xiang et al included a growth rate but no physical characterisation of pore length, morphology or ordering as a function of length.…”