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International Journal of Photoenergy
Volume 2014 (2014), Article ID 304580, 4 pages
http://dx.doi.org/10.1155/2014/304580
Research Article

Characterization of a-Si:H/c-Si Heterojunctions by Time Resolved Microwave Conductivity Technique

1Solar Energy Technology Laboratory, National Electronics and Computer Technology Center, 112 Thailand Science Park, Phahonyothin Road, Klong 1, Klong Luang, Pathumthani 12120, Thailand
2LPICM, CNRS-Ecole Polytechnique, Route de Saclay, 91128 Palaiseau, France
3Total New Energies, 24 Cours Michelet, La Défense 10, 92069 Paris La Défense, France

Received 17 December 2013; Revised 8 January 2014; Accepted 27 January 2014; Published 3 March 2014

Academic Editor: Peter Rupnowski

Copyright © 2014 Amornrat Limmanee 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.

Abstract

In heterojunction solar cells, a-Si:H/c-Si heterointerface is of significant importance, since the heterointerface characteristics directly affect junction properties and thus solar cell efficiency. In this study, we have performed time resolved microwave conductivity (TRMC) measurements on n-type c-Si wafers passivated on both sides with intrinsic and doped a-Si:H layers in order to investigate electrical property and passivation quality of the a-Si:H/c-Si heterojunctions. It was found that the TRMC decay time and decay curve shape varied with the laser wavelength and power intensity and also depended on sample structures. By using 1064 nm laser pulse with high excitation, differences in the decay curve shape between samples with and without p-n junction were observed. The samples containing p-n junction(s) had unique slow decay mode, after the initial fast decay, which we ascribed to the release of carriers from the low-mobility amorphous layer into the high-mobility crystalline wafer as the built-in field of the junction was restored. Experimental results suggest that the TRMC is useful nondestructive technique which is suitable for primary check of the a-Si:H/c-Si heterojunctions during the solar cell fabrication process.