Characterization of microstructures formed on MeV ion-irradiated silver films on Si(1 1 1) surfaces

Abstract

Ag epitaxial layers on silicon single crystal surfaces, upon MeV Si ion irradiation, undergo improvement in crystalline quality. This is often associated with remarkable changes in surface morphology. Growth of micron-sized (1-30 μm) islands has been observed on epitaxial Ag(1 1 1) thin films (~100 nm), deposited on Br-passivated Si(1 1 1) surfaces, when irradiated with energetic Si ions (1-12 MeV). This shows ion beam-induced mass transport in the Ag layer. The islands on the surface of the Ag films show a variation in height, diameter and number density as a function of ion energy as well as fluence. A detailed analysis with ion microprobe and atomic force microscopy is presented. Many islands interestingly appear to have a triplet pattern - the island, a depleted region around the island and a frozen wave packet. A tentative explanation for the formation of the triplet structure is given.