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

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.H₂ 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 SiF₄ (Tetrafluorosilane) as an additive gas during the amorphous silicon film deposition process using SiH₄. SiF₄ 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.