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O: Oberflächenphysik

O 29: Adsorption an Oberfl
ächen (III)

O 29.6: Vortrag

Donnerstag, 14. März 2002, 12:30–12:45, H43

Diffusion and nucleation mechanisms of metallic atoms on Si(111)7×7: Kinetic Monte Carlo simulations analysis — •C. Polop^1,2 and E. Vasco² — ¹I. Physikalisches Institut, RWTH Aachen, 52056 Aachen, Germany — ²Instituto de Ciencia de Materiales de Madrid - CSIC, Cantoblanco, 28049 Madrid, Spain

Due to the presence of reconstruction, and contrary to metals, semiconductors usually present a highly corrugate surface potential for diffusing adatoms. In particular, the 7×7 reconstruction plays a key role during first stages of adsorption on Si(111) surface. A tendency of the adatoms to an agglomeration inside the reconstruction half-cells as well as the presence of significant diffusion barriers at dimmer rows and corner holes have been previously described. However, the physical origin of the attraction between adatoms still remains unclear.

In this work, we get insight to the mechanisms that determinate the metal atom adsorption on the Si(111)7×7 surface by a KMC model and discuss those features of the kinetics that explain the origin of the attraction between adatoms. We compare the influence in the nucleation rate of the symmetric and asymmetric diffusions with the presence of long-range interaction. The analysis has been spread to the nucleation of energetic atoms by including the transient mobility. Our results compare favorably to adsorption data provided in the literature[1]: Pb, Ag, Sn and Y.

[1] J.M. Gómez-Rodríguez et al., Phys. Rev. Lett. 76 (1996) 799; P. Sobotík et al., Surf. Sci. 454-456 (2000) 847; O. Custance et al., Surf. Sci. 482-485 (2001) 1406