FLUX DEPENDENCE OF THE AG SI(111) GROWTH

We have studied the initial stages ((1 divided-by 2) ML) of the growth of Ag on Si(111) as a function of temperature T and deposition rate F to identify the operating diffusion mechanism. The specular beam inte nsity at 150 K shows short-lived oscillations which depend on the tota l amount of Ag deposited, irrespectively of the deposition rate, and s uggest the absence of thermal diffusion at this low temperature. Growt h studies at higher temperatures T greater-than-or-equal-to 473 K, mon itoring the formation of the square-root 3 x square-root 3 R30-degrees structure as a function of deposition rate, measure a non-thermal com ponent R0 > 50 angstrom to the diffusion length. The temperature depen dence of the square-root 3 growth is used to measure an activation ene rgy E(d) = (0.24 +/- 0.05) eV.