High-rate deposition of a-SiNx:H for photovoltaic applications by the expanding thermal plasma

Driven by the need for improvement of the economical competitiveness of photovoltaic energy, the feasibility of high-rate (>1 nm/s) amorphous silicon nitride (a-SiNx:H) deposited by the expanding thermal plasma (ETP) technique has been explored with respect to the application of the a-SiNx:H as functional antireflection coating on crystalline silicon solar cells. First, the deposition rate and the a-SiNx:H film properties, such as refractive index, Si, N, and H atomic density, and hydrogen bonding configurations, have been mapped for various operating conditions. From ellipsometry, elastic recoil detection, and infrared spectroscopy, it has been shown that deposition rates up to 20 nm/s can be reached with a fair film homogeneity and that the refractive index and the N/Si ratio can fully be tuned by the plasma composition while the hydrogen content can be controlled by the substrate temperature. Good antireflection coating performance of the a-SiNx:H has therefore been observed for monocrystalline silicon...