Effect of thermal annealing on the optical properties of high-energy Cu-implanted silica glass

Silica glasses implanted with 2 MeV Cu+ ions at various doses from 9.95x10( 16) to 2.2x10(17) ions/cm(2) were thermally annealed in air in between 600 degrees C and 1050 degrees C. Rutherford backscattering measurements were u sed to determine the concentration of implanted ions and their distribution s in the samples. The Cu distribution in the samples depended on the implan tation dose. Optical absorption spectra, measured in between 200 and 800 nm at room temperature, revealed a peak at about 560 nm, attributed to colloi dal Cu particles, for all the samples even before heat treatment, which ind icates the formation of particles even at lower doses, when high energy imp lantation is used. Using the equation derived from the framework of free-el ectron theory, the average radii of the Cu particles were determined from t he experimental surface plasmon absorption peaks. The average radius of Cu particles decreased slightly on annealing at 600 degrees C, suggesting the formation of additional small Cu precipitates at this temperature. However, the average radius of Cu particles increased as the annealing temperature increased from 800 degrees C to 1050 degrees C. The anomalies between the c alculated average radius of the particles and the absorption peak positions at higher annealing temperatures were explained. (C) 2000 Elsevier Science B.V. All rights reserved.