title: Ultrasmooth silver thin films deposited with a germanium nucleation layer.
abstract: We demonstrate an effective method for depositing smooth silver (Ag) films on SiO(2)/Si(100) substrates using a thin seed layer of evaporated germanium (Ge). The deposited Ag films exhibit smaller root-mean-square surface roughness, narrower peak-to-valley surface topological height distribution, smaller grain-size distribution, and smaller sheet resistance in comparison to those of Ag films directly deposited on SiO(2)/Si(100) substrates. Optically thin ( approximately 10-20 nm) Ag films deposited with approximately 1-2 nm Ge nucleation layers show more than an order of magnitude improvement in the surface roughness. The presence of the thin layer of Ge changes the growth kinetics (nucleation and evolution) of the electron-beam-evaporated Ag, leading to Ag films with smooth surface morphology and high electrical conductivity. The demonstrated Ag thin films are very promising for large-scale applications as molecular anchors, optical metamaterials, plasmonic devices, and several areas of nanophotonics.
authors.affiliation: Department of Electrical & Computer Engineering, Kemper Hall, University of California at Davis, One Shields Avenue, Davis, California 95616, USA.
authors.lastname: Logeeswaran Vj
authors.forename: Nobuhiko P
authors.initials: NP
authors.lastname: Kobayashi
authors.forename: M Saif
authors.initials: MS
authors.lastname: Islam
authors.forename: Wei
authors.initials: W
authors.lastname: Wu
authors.forename: Pratik
authors.initials: P
authors.lastname: Chaturvedi
authors.forename: Nicholas X
authors.initials: NX
authors.lastname: Fang
authors.forename: Shih Yuan
authors.initials: SY
authors.lastname: Wang
authors.forename: R Stanley
authors.initials: RS
authors.lastname: Williams
mesh_terms: D003460:Crystallization / Q000379:methods*; D004553:Electric Conductivity; D005857:Germanium / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008567:Membranes, Artificial; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D012666:Semiconductors; D012834:Silver / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D046911:Macromolecular Substances; D008567:Membranes, Artificial; D005857:Germanium; D012834:Silver