Chemical and electronic characterization of methyl-terminated Si(111) surfaces by high-resolution synchrotron photoelectron spectroscopy

Ralf Hunger, Rainer Fritsche, Bengt Jaeckel, Wolfram Jaegermann, Lauren J. Webb, Nathan S Lewis

Research output: Contribution to journalArticle

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Abstract

The chemical state, electronic properties, and geometric structure of methyl-terminated Si(111) surfaces prepared using a two-step chlorination/alkylation process were investigated using high-resolution synchrotron photoelectron spectroscopy and low-energy electron diffraction methods. The electron diffraction data indicated that the methylated Si surfaces maintained a (1×1) structure, where the dangling bonds of the silicon surface atoms were terminated by methyl groups. The surfaces were stable to annealing at 720 K. The high degree of ordering was reflected in a well-resolved vibrational fine structure of the carbon 1s photoelectron emission, with the fine structure arising from the excitation of C-H stretching vibrations having hν=0.38±0.01eV. The carbon-bonded surface Si atoms exhibited a well-defined x-ray photoelectron signal having a core level shift of 0.30±0.01eV relative to bulk Si. Electronically, the Si surface was close to the flat-band condition. The methyl termination produced a surface dipole of -0.4eV. Surface states related to πCH3 and σSi-C bonding orbitals were identified at binding energies of 7.7 and 5.4 eV, respectively. Nearly ideal passivation of Si(111) surfaces can thus be achieved by methyl termination using the two-step chlorination/alkylation process.

Original languageEnglish
Article number045317
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume72
Issue number4
DOIs
Publication statusPublished - Jul 15 2005

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Photoelectron spectroscopy
Synchrotrons
synchrotrons
photoelectron spectroscopy
high resolution
electronics
Chlorination
chlorination
Alkylation
Photoelectrons
alkylation
Carbon
photoelectrons
electron diffraction
fine structure
Atoms
Dangling bonds
Core levels
Low energy electron diffraction
Surface states

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Chemical and electronic characterization of methyl-terminated Si(111) surfaces by high-resolution synchrotron photoelectron spectroscopy. / Hunger, Ralf; Fritsche, Rainer; Jaeckel, Bengt; Jaegermann, Wolfram; Webb, Lauren J.; Lewis, Nathan S.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 72, No. 4, 045317, 15.07.2005.

Research output: Contribution to journalArticle

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