Desorption kinetics of surface species on Si(100)2x1 and Si(111)7x7 surfaces : theoretical and digital TPD studies

Liu, Yong (1994) Desorption kinetics of surface species on Si(100)2x1 and Si(111)7x7 surfaces : theoretical and digital TPD studies. University of Southampton, Doctoral Thesis.

Abstract

The possible basic surface species on clean Si(100)2x1 and Si(111)7x7 surfaces following adsorption of deuterium atoms, chlorine and/or bromine molecules were identified on the basis of the published LEED patterns, HREELS and surface IR spectra and particularly STM images as well as STS spectra. In each case chemical equilibrium equations have been proposed for the relevant surface species on the basis of surface structures. An appropriate kinetic lattice-gas model has been used in order to explain the experimental observations.

Experimentally, the desorption of various gaseous molecules from the Si(100)2x1 and Si(111)7x7 surfaces for the above systems has been investigated by scanning the digitized temperature-programmed desorption (TPD) spectra using a non-linear temperature ramp under the control of a computer. The experimental results have been analyzed using a TPD peak shape analysis method in conjunction with the appropriate theoretical model for each desorption channel in the recorded TPD spectra. Detailed kinetic information was obtained in all cases and the proposed theoretical models were tested. The main experimental setup includes a 500 mm i.d. UHV (≤2x10^-10 mbar) chamber and a differentially-pumped QMS detector.

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