Studies of adsorption and electron-induced dissociation of Fe(CO) 5 on Si(100)

Abstract

The adsorption and electron-stimulated decomposition properties of Fe(CO) 5 on Si(100) have been investigated. At substrate temperatures in the range 77–300 K, no chemisorption states are populated to a detectable extent. Physisorption at 77 K is observed, with a sticking probability of ≈ 0.2; TDS indicates that the heat of adsorption is constant at 33 ± 4 kJ mol −1 both in the monolayer and multilayer regimes and the desorption kinetics are suggestive of island formation. Prominent electron-stimulated desorption (ESD) and decomposition effects have been investigated. Fe(CO) 5 multilayers decompose by rapid ESD of iron carbonyls, whilst monolayer decomposition involves the evolution of O and CO species in a stepwise manner from the parent molecule. Cross-sections for the processes occurring are evaluated; the electron stimulated rate of FeCO bond cleavage is demonstrated to be more rapid than the rate of escape of oxygen containing entities from the surface and this is explained in terms of bond orientation effects.