Terrace-dependent nucleation of small Ag clusters on a five-fold icosahedral quasicrystal surface

Abstract

Nucleation of Ag islands on the five-fold surface of icosahedral Al–Pd–Mn is influenced strongly by trap sites. Submonolayers of Ag prepared by deposition at 365 K and with a flux of 1 × 10⁻³ monolayers/s exhibit a variation in Ag island densities across different terraces. Comparisons with previous work and with rate equation analysis indicate that trap sites are not saturated under these experimental conditions and that the difference in island densities is not necessarily due to variation in trap densities. While it could have a number of different origins, our results point to a terrace-dependent value of the effective diffusion barrier for Ag adatoms.

Acknowledgments

BU, CJJ, ARR, TAL and PAT were supported in this work by the Office of Science, Basic Energy Sciences, Materials Science Division of the US Department of Energy (USDOE). JWE was supported by NSF Grant CHE-0414378. The work was performed at Ames Laboratory, which is operated for the USDOE by Iowa State University under Contract No. W-7405-Eng-82. BU is thankful to Da-Jiang Liu for his help in writing Mathematica codes for the REA.