| The wide use of solar cells will be a feasible way to solve the energy and environmental protection problems. Poly-crystalline silicon solar cells are considered as the most promising cells in the future. How to increase properties of mc-Si substrates and improve the efficiency is the focus in solar cells filed. In paper effect of oxygen and carbon action on minority carrier lifetime in thermal process of mc-Si cell and properties of Si3N4 film and effects of antirefle-ction and passivation were studied.By means of FTIR and QSSPCD and OPTICAL MICROSCOPE during different thermal process, It is found that the diffusion of hydrogen may passivate the defects/boundaries and it is beneficial to the lifetime of mc-Si. Bulk lifetime of mc-Si showed better results annealing in O2 than that in N2 and annealing in two-step reflected better consequence than annealing in single-step. Concentraton of oxygen in two-step decreased greatly. Lifetime of Cz-Si showed tendency of decrease - rise - rerise, but Lifetime of mc-Si showed rise - decrease -rerise and foemed a number of oxygen precipitates after three step annealing in N2 ambient.Si3N4 thin films were deposited by Plasma Enhanced Chemical Vapour Deposition (PECVD), the characterization of SiN thin films was studied by spectral ellipsometry, infrared absorption spectroscopy (IR), X-ray Photoelectric Spectroscopy (XPS), quasi-steady state photocond-uctance decay (QSSPCD) measurements and reflection spectra etc. It is found the best deposition ambient and temperature. Hydrogen content have relations with the minority carrier lifetimes. To compare, electric properties of solar cells had a larger improvement after deposition of SiN films on the poly-crystalline solar cells.
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