SODIUM AND CHLORINE COADSORPTION ON Si(100)

Abstract

In this paper we study the adsorption of molecular chlorine on the Si(100)(2 × 1) surface and its interaction with sodium at room and elevated temperature in an ultrahigh vacuum. Cl is deposited dissociatively on the surface and forms SiCl 2 and SiCl 4. During Na deposition on the Cl-covered Si(100) surface, the substrate participates to a NaSiCl 2 compound formation, whereas Cl deposition on Na-covered Si(100) leads to NaCl formation, which is grown with the (100) plane parallel to the surface. After the completion of the NaCl formation, the excess Cl interacts with the substrate and forms Si–Cl compounds. The presence of Na on the surface prevents partly the chlorination of Si, depending on the amount of Na. At elevated temperatures, the NaCl dissociates according to the equation 2 NaCl + Si → Na 2 Cl + SiCl and desorbs.