title: Hierarchical ultrathin alumina membrane for the fabrication of unique nanodot arrays.
abstract: Ultrathin alumina membranes (UTAMs) as evaporation masks have been a powerful tool for the fabrication of high-density nanodot arrays and have received much attention in magnetic memory devices, photovoltaics, and nanoplasmonics. In this paper, we report the fabrication of a hierarchical ultrathin alumina membrane (HUTAM) with highly ordered submicro/nanoscale channels and its application as an evaporation mask for the realization of unique non-hexagonal nanodot arrays dependent on the geometrical features of the HUTAM. This is the first report of a UTAM with a hierarchical geometry, breaking the stereotype that only limited sets of nanopatterns can be realized using the UTAM method (with typical inter-pore distance of 100 nm). The fabrication of a HUTAM is discussed in detail. An improved, longer wet etching time than previously reported is found to effectively remove the barrier layer and widen the pores of a HUTAM. A growth sustainability issue brought about by pre-patterning is discussed. Spectral comparison was made to distinguish the UTAM nanodots and HUTAM nanodots. Our results can be an inspiration for more sophisticated applications of pre-patterned anodized aluminum oxide in photocatalysis, photovoltaics, and nanoplasmonics.
authors.affiliation: State Key laboratory of Supramolecular Structure and Materials, Institute of Theoretical Chemistry, Jilin University, 2699 Qianjin Ave., Changchun, People's Republic of China.
authors.forename: Yuyang
authors.initials: Y
authors.lastname: Wang
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: Hailong
authors.initials: H
authors.lastname: Wang
authors.forename: Xinnan
authors.initials: X
authors.lastname: Wang
authors.forename: Ming
authors.initials: M
authors.lastname: Cong
authors.forename: Weiqing
authors.initials: W
authors.lastname: Xu
authors.forename: Shuping
authors.initials: S
authors.lastname: Xu