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Proceedings Paper

Semiconductor spectroscopy and ablation processes with the Vanderbilt University FEL
Author(s): Norman H. Tolk; Royal G. Albridge; Alan V. Barnes; Jim T. McKinley; H. B. Nielsen; Akira Ueda; J. F. Smith; Jeffrey L. Davidson; M. L. Languell; Carlo Coluzza; E. Tuncel; Giorgio Margaritondo
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Paper Abstract

This paper describes the results of novel experiments made possible by the recently commissioned Vanderbilt Free-Electron Laser (VU-FEL_, the brightest tunable midinfrared FEL in the world. We emphasize two classes of experiments, novel semiconductor spectroscopies and wavelength-dependent laser ablation studies. Both take advantage of the high brightness and the tunability of the FEL. We have recently demonstrated the feasibility of measuring semiconductor heterojunction band discontinuities using the internal photoemission (IPE) technique and report the results for the cases of GaAs/GaAlAs and a-Ge/GaAs. The basic physical mechanism of IPE is that a photocurrent is produced by optically pumping electrons over the conduction band discontinuity (Delta) Ec. A photocurrent threshold is observed when the photon energy exceeds (Delta) Ec. Because IPE is optical in nature, (Delta) Ec can be determined with unprecedented accuracy (5 meV). By comparison, the best known direct method of measuring band discontinuities (UPS or XPS) achieves accuracies of only 100 meV.

Paper Details

Date Published: 14 July 1993
PDF: 9 pages
Proc. SPIE 1854, Free-Electron Laser Spectroscopy in Biology, Medicine, and Materials Science, (14 July 1993); doi: 10.1117/12.148046
Show Author Affiliations
Norman H. Tolk, Vanderbilt Univ. (United States)
Royal G. Albridge, Vanderbilt Univ. (United States)
Alan V. Barnes, Vanderbilt Univ. (United States)
Jim T. McKinley, Vanderbilt Univ. (United States)
H. B. Nielsen, Vanderbilt Univ. (United States)
Akira Ueda, Vanderbilt Univ. (United States)
J. F. Smith, Vanderbilt Univ. (United States)
Jeffrey L. Davidson, Vanderbilt Univ. (United States)
M. L. Languell, Vanderbilt Univ. (United States)
Carlo Coluzza, Ecole Polytechnique Federale de Lausanne (Switzerland)
E. Tuncel, Ecole Polytechnique Federale de Lausanne (Switzerland)
Giorgio Margaritondo, Ecole Polytechnique Federale de Lausanne (Switzerland)

Published in SPIE Proceedings Vol. 1854:
Free-Electron Laser Spectroscopy in Biology, Medicine, and Materials Science
H. Alan Schwettman, Editor(s)

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