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

Hunger, Ralf and Fritsche, Rainer and Jaeckel, Bengt and Jaegermann, Wolfram and Webb, Lauren J. and Lewis, Nathan S. (2005) Chemical and electronic characterization of methyl-terminated Si(111) surfaces by high-resolution synchrotron photoelectron spectroscopy. Physical Review B, 72 (4). Art. No. 045317. ISSN 1098-0121. http://resolver.caltech.edu/CaltechAUTHORS:HUNprb05

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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 hnu=0.38±0.01 eV. The carbon-bonded surface Si atoms exhibited a well-defined x-ray photoelectron signal having a core level shift of 0.30±0.01 eV relative to bulk Si. Electronically, the Si surface was close to the flat-band condition. The methyl termination produced a surface dipole of –0.4 eV. Surface states related to piCH3 and sigmaSi-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.


Item Type:Article
Additional Information:©2005 The American Physical Society (Received 19 November 2004; accepted 15 March 2005; published 8 July 2005) We gratefully acknowledge the National Science Foundation, grant No. CHE-0213589, for support of this work (N.S.L. and L.J.W.) and for providing financial assistance to L.J.W. W.J. acknowledges the travelling support of the Deutsche Forschungsgemeinschaft, DFG Grant No. JA 85910-1. The support of the BMBF for setting-up and running SoLiAS at BESSY (Contracts Nos. 05 KS1RD1/0 and 05 KS4RD1/0, R.H. and W.J.) and travel grants (05 ES3XBA/5) are gratefully acknowledged.
Subject Keywords:silicon; elemental semiconductors; surface reconstruction; X-ray photoelectron spectra; passivation; low energy electron diffraction; annealing; photoemission; dangling bonds; vibrational modes; core levels; binding energy; excited states; fine structure
Record Number:CaltechAUTHORS:HUNprb05
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:HUNprb05
Alternative URL:http://dx.doi.org/10.1103/PhysRevB.72.045317
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2420
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:03 Apr 2006
Last Modified:26 Dec 2012 08:49

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