STICKING PROBABILITY AND ADSORPTION PROCESS OF NH3 ON SI(100) SURFACE

The absolute sticking probability of NH3 molecules on Si(100) surface was measured using a NH3 molecular beam. Also taking into account the measured angular distribution of the scattered NH3 molecules, it is co ncluded that the adsorption of NH3 follows a trapping-mediated mechani sm. From the dependence of the initial sticking probability on the sam ple temperature, the difference between the activation energies for de sorption and chemisorption from a precursor state, (E-des-E-ad), was e stimated. The coverage dependence of the sticking probability, s(Theta ), was also measured. From the sample temperature dependence of s(Thet a), parameters for the migration of the NH3 precursor were derived usi ng the Kisliuk model. The kinetics of the adsorption of NH3 on the Si( 100) is discussed on the basis of this model. (C) 1998 Elsevier Scienc e B.V. All rights reserved.