CHLORINE SILICON SURFACE-REACTIONS UNDER HEATING

Reactions on Cl-adsorbed Si(111) and Si(100) surfaces - (Cl/Si(111) and Cl/Si(100)) - under heating in ultrahigh vacuum (UHV) and in a Cl2 atmosphere were studied. Auger electron spectroscopy (AES) and low-energy electron energy loss spectroscopy (LEELS) were used for examination of surface changes. Heating in UHV at 820-degrees-C for 30 s successfully removed almost all Cl atoms, both on Cl/Si(111) and Cl/Si(100). Variance in LEELS spectra shows that decomposition of SiClx (x > 1), a small amount of which was present on Cl/Si(111), occurs under heating on Si(111) both in UHV and in Cl2 and desorbs reaction products, leaving the Si-Cl bonds on the surfaces. Such Si-Cl bonds specific to those on Cl/Si(111) are formed also on Cl/Si(100) heated in Cl2 at 820-degrees-C. On Cl/Si(100) heated in Cl2, there are various surface changes: relaxation of the 2 x 1 structure remaining on the Cl/Si(100), desorption of reaction products, and formation of Si-Cl bonds specific to those on Cl/Si(111). The Si-Cl bonds, both on Cl/Si(111) and Cl/Si(100), decomposed under longer heating and under heating at higher temperatures in UHV.