Highly controlled microcrystalline silicon growth using in-situ Raman spectroscopy

The growth of PV grade microcrystalline silicon using plasma enhanced chemical vapor deposition is realized in a narrow process window. Thus, the stability and the controllability of deposition processes is challenging. Process drifts occur between two different deposition runs or within a single deposition run, which can lead to microcrystalline silicon material that is not optimal for thin-film silicon device applications. In the present work, we use in-situ Raman spectroscopy during silicon deposition to study the growth with high temporal and depth resolution in growth direction. It is shown that with a homogeneous crystallinity profile in growth direction the solar device conversion efficiency was increased from 7.29% to 7.67%. Hence, in this paper it is demonstrated that using in-situ Raman spectroscopy is suitable for highly controlled microcrystalline silicon processing.