Nucleation and surface diffusion in pulsed laser deposition of Fe on Mo(1 1 0)

A kinetic analysis of Fe islands growth on Mo(1 1 0) in the sub-monolayer range as a function of temperature is presented for the pulsed laser deposition (PLD) epitaxial technique. It has allowed us to determine the corresponding diffusion barrier Ed=0.1±0.05 eV and the diffusion attempt frequency ν0=8×1011±1 Hz. Numerical integration of the standard kinetic differential equations is used to describe the specificity of the pulsed character of PLD. Good agreement is found with experimental results. A comparison to reported molecular beam epitaxy (MBE) sub-monolayer growth of Fe at 300 K is also considered. The PLD technique is demonstrated to lead to an increase of the diffusion rate by 4 orders of magnitude, presumably as a consequence of the higher energy of the impinging species. Incidentally, this increase of diffusion rate is compensated by the large instantaneous deposition flux leading to identical densities using MBE or PLD for Fe/Mo(1 1 0) at 300 K.