Solar cell lifetime evaluation of using different Si-based precursor gases, SiH4 and SiF4

• Main Authors: Hung-Ming Chen, Nasu, A., Jurcik, B., Chevrel, H., Techi Wong, Jun-Chin Liu
• Format: Conference Proceeding
• Language: English
• Subjects: Amorphous materials; Amorphous silicon; Atomic layer deposition; Bonding; Degradation; Electron traps; Filling; Gases; Photovoltaic cells; Semiconductor films
• ISSN: 0160-8371
• DOI: 10.1109/PVSC.2009.5411635

In amorphous silicon (a-Si), Si atoms are not all bonded to 4 other silicon atomes in an ordered manner. and this leads to the formation of defects such as Si dangling bonds.H 2 used in the a-Si:H film deposition process passivate the dangling bonds by forming Si-H bonds, thus reducing the defect density. However H* in thin hydrogeneited a-Si films is very reactive especially under light exposure and can successfully break Si-Si bonds to create Si-H and a Si* dangling bond. In turn this defects can trap the electron-holes pairs leading to the degradation of cell efficiency. This is believed to be one of the main reasons for the so-called Staebler-Wronski (S-W) effect. In our current study, we add SiF 4 (Tetrafluorosilane) as an additive gas during the amorphous silicon film deposition process using SiH 4 . SiF 4 is used as an additive to incorporate small controlled amounts of [F] in the amorphous film, which may stabilize the free dandling bond and may decrease the Staebler-Wronski effect. The effects on complete cell performance parameters, such as the cell efficiency, filling factor, Jsc, Voc and light-soaking degradation results are also included in this study.