In situ film transmittance using the plasma as light source: a case study of thin silicon film deposition in the microcrystalline growth regime

In-situ film transmittance using the plasma as light source is introduced as a novel in-situ real-time deposition rate and film thickness monitor. It also enables the estimation of the absorption coefficient at short wavelengths. In the experimental setup the light emitted by the plasma passes through a growing thin silicon film on a transparent substrate and is detected by a simple optical emission spectrometer. From the interference fringes the deposition rate is determined in-situ with high accuracy and on the basis of film absorption the transition from microcrystalline- to amorphous silicon is mapped. Results are corroborated by ex-situ thickness measurements, and solar cell analyse