Colloid formation effects on depth profile of implanted Ag in SiO2 glass

Abstract

Ag+ ions of 150 keV were implanted into SiO2 glasses at room temperature to doses of 0.1–60×1016/cm2. Formation of Ag colloids in SiO2 glasses was observed by the cross-sectional transmission electron microscopy and optical absorption spectra. An anticorrelation is found between the Ag colloid size and the width of the Ag depth profile measured by Rutherford backscattering spectrometry. At low dose, the size of Ag colloids is small (<10 nm in diameter) and the Ag depth profile is close to that of a simulation calculation. At increasing dose, small Ag colloids and/or Ag atoms aggregate to grow up to ∼40 nm and the width of the Ag depth profile is reduced to ∼50 nm, which is close to the above colloid size, indicating that the size of a Ag colloid particle controls the Ag depth profile. The size and shape of colloids are the keys which modify the optical properties by metallic ion implantation for applications such as optical isolators.