Structure, stability and photoelectronic properties of transition films from amorphous to microcrystalline silicon

A series of hydrogenated silicon films near the threshold of crystallinity was prepared by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) from a mixture of SiH4 diluted in H2. The effect of hydrogen dilution ratios RH=[H2]/[SiH4] on microstructure of the films was investigated. Photoelectronic properties and stability of the films were studied as a function of crystalline fraction. The results show that more the crystalline volume fraction in the silicon films, the higher mobility life-time product (μτ), better the stability and lower the photosensitivity. Those diphasic films contained 8%-31% crystalline volume fraction can gain both the fine photoelectronic properties and high stability. In the diphasic (contained 12% crystalline volume fraction) solar cell, we obtained a much lower light-induced degradation of ∼2.9%, with a high initial efficiency of 10.01% and a stabilized efficiency of 9.72% (AM1.5, 100 mW/cm2).