title: Nanoporous SiO2 thin films made by atomic layer deposition and atomic etching.
abstract: A new route to prepare nanoporous SiO2 films by mixing atomic-layer-deposited alumina and silica in an Å-scale is presented. The selective removal of Al2O3 from the composites using wet chemical etching with phosphoric acid resulted in nanoporous thin SiO2 layers. A diffusion-controlled dissolution mechanism is identified whereby an interesting reorganization of the residual SiO2 is observed. The atomic scale oxide mixing is decisive in attaining and tailoring the film porosity. The porosity and the refractive index of nanoporous silica films were tailored from 9% to 69% and from 1.40 to 1.13, respectively. The nanoporous silica was successfully employed as antireflection coatings and as diffusion membranes to encapsulate nanostructures.
authors.affiliation: Institute of Applied Physics, Abbe Center of Photonics, Albert-Einstein-Straße 15, D-07745, Jena, Germany.
authors.forename: Lilit
authors.initials: L
authors.lastname: Ghazaryan
authors.forename: E-Bernhard
authors.initials: EB
authors.lastname: Kley
authors.forename: Andreas
authors.initials: A
authors.lastname: Tünnermann
authors.forename: Adriana
authors.initials: A
authors.lastname: Szeghalmi