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Research Letters in Materials Science
Volume 2008, Article ID 643743, 4 pages
Research Letter

The Charge Transport Properties of a HWCVD a-Si:H Thin Film under Bending Pressure

1Solid State Physics Department, National Research Center (NRC), Dokki, 12332 Cairo, Egypt
2IV. Physics Institute, University of Göttingen, Friedrich-Hund Platz 1, 37077 Göttingen, Germany
3Department of Physics and Astronomy, University of California, Los Angeles, CA 90024, USA

Received 15 August 2007; Accepted 21 January 2008

Academic Editor: Jeffrey T. Glass

Copyright © 2008 M. Boshta et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The transient thermoelectric effects (TTEs) method is used to measure the ambipolar space charge built up in a low-pressure hot wire chemical vapor deposition (HWCVD) technique a-Si:H layer deposited on a glass substrate. The stage 2 TTE-transients yield the trap state density difference with and without bending pressure up to 9 bars. The a-Si:H sample shows a reduction of the negative storage peaks at 0.045 eV and 0.026 eV with increasing pressure, while the positive (hole trap) peak and the zero crossing practically do not change with the pressure. At the maximum bending pressure, the negative peaks are almost zero and shifted into the band gap or toward the conduction band. Our result shows that it is necessary to produce and mount hydrogenated thin film solar cell stress-free.