Radiation damage to alkyl chain monolayers on semiconductor substrates investigated by electron spectroscopy

Fabrice Amy, Calvin K. Chan, Wei Zhao, Jaehyung Hyung, Masaki Ono, Tomoki Sueyoshi, Satoshi Kera, Guy Nesher, Adi Salomon, Lior Segev, Oliver Seitz, Hagay Shpaisman, Achim Schöll, Marc Haeming, Till Böcking, David Cahen, Leeor Kronik, Nobuo Ueno, Eberhard Umbach, Antoine Kahn

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34 Scopus citations


Monolayers of alkyl chains, attached-through direct Si-C bonds to Si(111), via phosphonates to GaAs(100) surfaces, or deposited as alkyl-silane monolayers on SiO2, are investigated by ultraviolet and inverse photoemission spectroscopy and X-ray absorption spectroscopy. Exposure to ultraviolet radiation from a He discharge lamp, or to a beam of energetic electrons, leads to significant damage, presumably associated with radiation- or electron-induced H-abstraction leading to carbon-carbon double-bond formation in the alkyl monolayer. The damage results in an overall distortion of the valence spectrum, in the appearance of (occupied) states above the highest occupied molecular orbital of the alkyl molecule, and in a characteristic (unoccupied state) π* resonance at the edge of the carbon absorption peak. These distortions present a serious challenge for the interpretation of the electronic structure of the monolayer system. We show that extrapolation to zero damage at short exposure times eliminates extrinsic features and allows a meaningful extraction of the density of state of the pristine monolayer from spectroscopy measurements.

Original languageEnglish (US)
Pages (from-to)21826-21832
Number of pages7
JournalJournal of Physical Chemistry B
Issue number43
StatePublished - Nov 2 2006

All Science Journal Classification (ASJC) codes

  • Materials Chemistry
  • Surfaces, Coatings and Films
  • Physical and Theoretical Chemistry


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