title: Optical properties and oxidation of α-phase Ag-Al thin films.
abstract: We investigate a series of Ag-Al thin films containing up to 12 at% Al with the purpose of discovering whether these alloys would be a better choice for nanophotonic applications than pure Ag. Variable angle spectroscopic ellipsometry, AFM, x-ray diffraction and density functional theory are applied to explore and characterize the materials. Electromagnetic simulations of optical properties are used to place the results into a theoretical framework. We find that the increase in electron-to-atom ratio associated with the Al additions changes the optical properties: additions of the order of 1-2 at% Al are beneficial as they are associated with favorable changes in the dielectric function, but for greater additions of Al there is a flattening of the absorption edge and an increase in optical loss. In addition, contents of more than about 2 at% Al are associated with the onset of time-dependent intergranular oxidation, which causes a pronounced dip in the reflectance spectrum at about 2.3-2.4 eV (∼500-540 nm).
authors.affiliation: Institute for Nanoscale Technology, University of Technology Sydney, PO Box 123, Broadway, NSW 2007, Australia.
authors.forename: Kaludewa S B
authors.initials: KS
authors.lastname: De Silva
authors.forename: Vicki J
authors.initials: VJ
authors.lastname: Keast
authors.forename: Angus
authors.initials: A
authors.lastname: Gentle
authors.forename: Michael B
authors.initials: MB
authors.lastname: Cortie