Ultra-thin ultra-smooth and low-loss silver films on a germanium wetting layer

Weiqiang Chen, Purdue University - Main Campus
Mark D. Thoreson, Purdue University - Main Campus
Satoshi Ishii, Purdue University - Main Campus
Alexander V. Kildishev, Birck Nanotechnology Center, School of ECE
V. M. Shalaev, Birck Nanotechnology Center and School of Electrical and Computer Engineering, Purdue University

Abstract

We demonstrate a method to fabricate ultra-thin, ultra-smooth and low-loss silver (Ag) films using a very thin germanium (Ge) layer as a wetting material and a rapid post-annealing treatment. The addition of a Ge wetting layer greatly reduces the surface roughness of Ag films deposited on a glass substrate by electron-beam evaporation. The percolation threshold of Ag films and the minimal thickness of a uniformly continuous Ag film were significantly reduced using a Ge wetting layer in the fabrication. A rapid post-annealing treatment is demonstrated to reduce the loss of the ultra-thin Ag film to the ideal values allowed by the quantum size effect in smaller grains. Using the same wetting method, we have also extended our studies to ultra-smooth silver-silica lamellar composite films with ultra-thin Ag sublayers. (C) 2010 Optical Society of America

Discipline(s)

Engineering | Nanoscience and Nanotechnology