NIR diode laser spectroscopy of HF and HCl at multiple points in the atmospheric pressure CVD of tin oxide films

This paper reports the in situ application, for the first time, of simultaneous multispecies, multipoint near-infrared diode laser absorption spectroscopy (NIRDLAS) to the deposition of thin films by atmospheric pressure chemical vapour deposition (APCVD). Hydrogen fluoride as a precursor and hydrogen chloride as a reaction product were detected in tin oxide thin film deposition in a roll-to-roll pilot reactor. The process is commercially important, and we demonstrate results from the application of the technology to the production scale manufacturing process for photovoltaic coatings.