AVS 51st International Symposium
    Semiconductors Wednesday Sessions
       Session SC-WeA

Paper SC-WeA9
Lattice Constant Differences and Their Affect on the Surface Bonding of In@sub 2@O and Ga@sub 2@O on GaAs and InAs

Wednesday, November 17, 2004, 4:40 pm, Room 304C

Session: Narrow Gap Semiconductors
Presenter: M.J. Hale, University of California, San Diego
Authors: M.J. Hale, University of California, San Diego
D.L. Winn, University of California, San Diego
J.Z. Sexton, University of California, San Diego
M. Passlack, University of California, San Diego
A.C. Kummel, University of California, San Diego
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The atomic bonding structures formed upon deposition of In@sub 2@O on GaAs(001)-c(2x8)/(2x4) and InAs(001)-c(2x8)/(2x4) were identified through scanning tunneling microscopy and density functional theory calculations. These results were compared to the surface bonding structure of Ga@sub 2@O deposited on GaAs(001)-c(2x8)/(2x4). It was found that In@sub 2@O forms three distinct bonding configurations on the GaAs(001)-c(2x8)/(2x4) surface: two different configurations which span the trough, and one which inserts into row arsenic dimer pairs. When In@sub 2@­­O was deposited on the InAs(001)-c(2x8)/(2x4) surface only the row As dimer pair site was observed. This effect is attributed to the In@sub 2@O molecule being large enough to span the 8.0Å trough of the GaAs(001)-c(2x8)/(2x4) surface, but too small to span the 8.6Å trough of InAs(001)-c(2x8)/(2x4). The In@sub 2@O bonding site on InAs(001)-c(2x8)/(2x4) is analogous to the binding site for Ga@sub 2@O on GaAs(001)-c(2x8)/(2x4), where Ga@sub 2@O is found to bond only in row arsenic dimer pairs. The change in lattice constant between InAs and GaAs is also found to have an affect on Fermi level pinning. Through experiments and DFT calculations, we have shown that In@sub 2@O pins GaAs whereas Ga@sub 2@O does not. DFT calculations also show that we should not expect In@sub 2@O to pin InAs. Our results show that a modest change in lattice constant can dramatically alter the adsorbate bonding and electronic structure via a change in site selectivity.