No abstract

Dense hydrogenated silicon nitride (SiNx:H) layers for photovoltaics are made by Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition (AP‐PECVD). The dependence of morphology, chemical, optical and passivation properties of the thin films on the plasma reactor configuration, the mode of homogeneous DBD (glow, Townsend, RF, nano pulsed) and the SiH4/NH3 gas flow ratio are investigated. Avoiding gas recirculation, improving thin film homogeneity through the electrode length and the plasma modulation appear as key points. Silicon solar cells made with AP‐PECVD SiN antireflective coating have the same efficiency as standard low pressure PECVD cells, showing the great potential of AP‐PECVD.

This paper describes an optical setup built to record Fourier transform infrared (FTIR) absorption spectra in an atmospheric pressure plasma with a spatial resolution of 2 mm. The overall system consisted of three basic parts: (1) optical components located within the FTIR sample compartment, making it possible to define the size of the infrared beam (2 mm × 2 mm over a path length of 50 mm) imaged at the site of the plasma by (2) an optical interface positioned between the spectrometer and the plasma reactor. Once through the plasma region, (3) a retro-reflector module, located behind the plasma reactor, redirected the infrared beam coincident to the incident path up to a 45° beamsplitter to reflect the beam toward a narrow-band mercury-cadmium-telluride detector. The antireflective plasma-coating experiments performed with ammonia and silane demonstrated that it was possible to quantify 42 and 2 ppm of these species in argon, respectively. In the case of ammonia, this was approximately three times less than this gas concentration typically used in plasma coating experiments while the silane limit of quantification was 35 times lower. Moreover, 70% of the incoming infrared radiation was focused within a 2 mm width at the site of the plasma, in reasonable agreement with the expected spatial resolution. The possibility of reaching this spatial resolution thus enabled us to measure the gaseous precursor consumption as a function of their residence time in the plasma.