AVS 49th International Symposium
    Surface Science Tuesday Sessions
       Session SS3-TuA

Paper SS3-TuA9
Room Temperature Growth and Thermal Sintering of Ag and Pd on Flat Ultra-thin SiO@sub 2@ and MoO@sub 2@ Films

Tuesday, November 5, 2002, 4:40 pm, Room C-112C

Session: Metal/Oxide Surfaces
Presenter: A.K. Santra, Texas A&M University
Authors: A.K. Santra, Texas A&M University
B.K. Min, Texas A&M University
D.W. Goodman, Texas A&M University
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The initial growth morphology of Ag and Pd particles has been investigated on epitaxial ultra-thin MoO2(100) and SiO2 films using STM. The room temperature growth of Ag and Pd particles is invariant with respect to the thickness of the SiO2 film, however, with increasing surface temperature the Pd particles undergo a 3Dè 2D transition on a 0.5nm thick SiO2 film and increase in particle size on films with a thickness >0.8nm. In contrast, Ag particles on a MoO2(100) substrate show striking differences with respect to the particle size distribution as a function of the oxide film thickness at room temperature. These results indicate that the initial growth and thermal sintering of metal particles depend critically on the strength of the metal-support interaction. The preparation procedure for these flat ultra-thin films on Mo(112) will be discussed relative to the LEED and highly resolved STM data. Furthermore, STS data indicate that a minimum thickness (3 - 4 Si-atomic equivalent layers) is necessary to obtain a bulk-like band-gap for SiO2 ultra-thin films, in excellent agreement with results recently reported by Muller and co-workers [Nature 399 (1999) 758] for Si/SiO2/Si gate-oxide samples.