A versatile ultra-thin Au nanomesh from a reusable anodic aluminium oxide (AAO) membrane

Abstract

We demonstrated multiple replications of versatile ultra-thin Au nanomeshes from a single porous anodic aluminium oxide (AAO) membrane as a reusable replication master. A bilayered film of Ag and Au was sequentially deposited on nanoporous AAO (i.e., Au/Ag/AAO), in which the Ag layer sandwiched in-between the Au layer and AAO serves as a sacrificial layer for separating the Au film from the oxide membrane during selective wet-chemical etching of Ag in HNO₃ solution. The structure of the separated Au film is characterized by a free-standing nanomesh, the hole array pattern and pitch distance of which are defined by the AAO replication master. Ultra-thin Au meshes can be transferred onto substrates of choice without any structural failure. On the other hand, our repeated replication experiments have revealed that a single porous AAO replication master can be reused more than 30 times without significant structural changes. In the present work, we demonstrated the versatility of replicated Au nanomeshes in various nanofabrications, including preparation of extended arrays of Si nanowires (SiNWs) by metal-assisted chemical etching of silicon wafers and surface patterning of polymeric substrates with sub-100 nm resolution. The applicability of Au meshes as an electrode for flexible devices was manifested by comparable resistance values of Au meshes on the polymer substrate, viz., polyethylene terephthalate (PET), to a continuous Au film and stable I–V behaviours regardless of its bending state. The present approach of multiple replications of metal meshes from a single AAO membrane can be readily extended to other metallic materials and is time- and cost-effective compared to conventional lithographic methods.