Chlorine adsorption on Si(111) studied by optical methods

The adsorption process of chlorine on Si(1 1 1) has been studied by means o f real time surface differential reflectance (SDR) spectroscopy and second harmonic generation (SHG). The structure observed at 3.6 eV in SDR spectra is attributed to transitions including Si-Cl antibonding states. However, t he overall feature is due to the removal of the electronic states of the cl ean surface. Developments of adsorption on Si adatom dangling bonds and bre aking of adatom back bonds are obtained from SDR spectra and second harmoni c (SH) intensity. They are well fit by the solutions of the rate equations under the assumption of adsorption of atoms without migration, and the init ial sticking probability on the dangling bonds and the initial breaking pro bability of the back bonds are determined. Dependence of the adsorption kin etics on the carrier concentration is briefly reported. (C) 2001 Elsevier S cience B.V. All rights reserved.