AVS 61st International Symposium & Exhibition
    Surface Science Tuesday Sessions
       Session SS+NS-TuA

Paper SS+NS-TuA12
Collective Multi-Atom Diffusion in Ag/Ge(110) 1D Nanoisland Growth

Tuesday, November 11, 2014, 6:00 pm, Room 309

Session: Nanostructures: Growth, Reactivity and Catalysis
Presenter: Shirley Chiang, University of California, Davis
Authors: S. Chiang, University of California, Davis
C.H. Mullet, University of California, Davis
M.C. Tringides, Iowa State University and Ames Lab-USDOE
M.S. van Zijll, University of California, Davis
B.H. Stenger, University of California, Davis
E.S. Huffman, University of California, Davis
D.J. Lovinger, University of California, Davis
E.C. Poppenheimer, University of California, Davis
Correspondent: Click to Email
The growth of Ag deposited on Ge(110) was studied with low energy electron microscopy (LEEM) and scanning tunneling microscopy (STM). The LEEM studies showed the formation of long, one-dimensional (1D) multi-height islands over the temperature range 430C-530C. During deposition, the length of the islands increases at a constant rate (~106 atoms/sec reaching ~20 microns) and constant width (100-200nm) for 9ML total deposition. Stochastic diffusion cannot account for these very high island growth rates. When smaller islands decay, the rate is ~2x107 atoms/sec, which is also exceedingly fast, based on the Ag diffusion and detachment barriers. These high rates are not consistent with independent adatom events and imply multi-atom correlated diffusion. Such collective mass transport must be related to the mobility of the wetting layer. STM images show the crystalline structure of the 1D Ag islands and also indicate that the reconstructed regions between the islands consist of bare Ge. These data are corroborated by LEEM IV curves. Together, they confirm that the wetting layer provides the material for the islands to grow at these high rates.