Development of Optimal Nanocrystalline Absorption Layer for Thin Film Silicon Solar Cell Applications

摘要

To obtain an optimum absorption layer based on hydrogenated polymorphous and nanocrystalline silicon thin films in a plasma-enhanced chemical vapor deposition, radio frequency (RF) power was varied from 25 W to 100 W using a mixture of dichlorosilane and hydrogen. By Raman spectroscopy, the crystalline fraction was found to be varied from 7% to 69%, and RF power value of 75 W was found to be suitable with an appropriate mixture of amorphous and crystalline phases, respectively. Thickness measurements performed by profilometry were cross-checked with the value obtained from the cross-sectional scanning electron microscopy micrographs. Micrographs obtained using high-resolution transmission electron microscopy confirmed the presence of silicon nanocrystals in the range of 2-5 nm with a strong probability of confinement effect. B and gap value of 1.55 eV at 75 W upheld the suitability of this particular RF power for active absorption layer, which has also shown maximum photosensitivity.