TEMPERATURE-DEPENDENCE OF THIN OXIDE FILM GROWTH ON FE(110)

An Fe(110) surface was exposed to 10(-4) Pa O2 in the temperature rang e 298-523 K and the kinetics of the growth of oxide layers up to thick nesses of 4 nm has been investigated using ellipsometry. The data are compared to results obtained previously on Fe(100). On Fe(100) the oxi de growth process above 423 K can be succesfully described in a quanti tative manner, assuming that thermionic emission of electrons from the metal into the conduction band in the oxide is the rate-limiting step . The crucial parameter in this process is the metal-oxide work functi on. It is indeed observed that the growth kinetics at 448 and 473 K ar e in good agreement with calculations based on thermionic emission, as suming a metal-to-oxide work function on Fe(l 10) that is 0.06 eV larg er than on Fe(100).