Table of Contents Author Guidelines Submit a Manuscript
International Journal of Photoenergy
Volume 2014, Article ID 579176, 7 pages
Research Article

Development of Hydrogenated Microcrystalline Silicon-Germanium Alloys for Improving Long-Wavelength Absorption in Si-Based Thin-Film Solar Cells

Department of Photonics, National Chiao Tung University, 1001 University Road, Hsinchu 300, Taiwan

Received 25 April 2014; Accepted 9 July 2014; Published 22 July 2014

Academic Editor: Serap Gunes

Copyright © 2014 Yen-Tang Huang 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.


Hydrogenated microcrystalline silicon-germanium (μc- :H) alloys were developed for application in Si-based thin-film solar cells. The effects of the germane concentration and the hydrogen ratio on the μc- :H alloys and the corresponding single-junction thin-film solar cells were studied. The behaviors of Ge incorporation in a- :H and μc- :H were also compared. Similar to a- :H, the preferential Ge incorporation was observed in μc- :H. Moreover, a higher significantly promoted Ge incorporation for a- :H, while the Ge content was not affected by in μc- :H growth. Furthermore, to eliminate the crystallization effect, the 0.9 μm thick absorbers with a similar crystalline volume fraction were applied. With the increasing , the accompanied increase in Ge content of μc- :H narrowed the bandgap and markedly enhanced the long-wavelength absorption. However, the bias-dependent EQE measurement revealed that too much Ge incorporation in absorber deteriorated carrier collection and cell performance. With the optimization of and , the single-junction μc- :H cell achieved an efficiency of 5.48%, corresponding to the crystalline volume fraction of 50.5% and Ge content of 13.2 at.%. Compared to μc-Si:H cell, the external quantum efficiency at 800 nm had a relative increase by 33.1%.