K. Pedersen et al., DEPOSITION AND GROWTH OF AG ON SI(111) SURFACES STUDIED BY OPTICAL 2ND-HARMONIC GENERATION, Surface and interface analysis, 26(12), 1998, pp. 872-875
Optical second-harmonic generation has been used to follow in situ the
growth of thin Ag films deposited on Si(111) under various substrate
conditions and temperatures. This method is particularly sensitive to
the microscopic structure of the deposited Ag films. Thus, island form
ation is found to enhance the second-harmonic signal, and strongly tem
perature-dependent island formations were indeed observed at lower Ag
coverages. For a film thickness above 25 monolayers, identical film ro
ughness characteristics were found for growth temperatures between 200
and 450 K and for different types of substrate reconstruction. A laye
r-by-layer growth mode can be obtained for low substrate temperatures
or for surface passivation by oxygen or hydrogen. In such cases the se
cond-harmonic signal oscillates. The period of oscillation is 10 monol
ayers. These oscillations are due to the formation of quantum-well sta
tes in the film. (C) 1998 John Wiley & Sons, Ltd.