Crystalline silicon surface passivation with SiON:H films deposited by medium frequency magnetron sputtering

Hydrogenated silicon oxynitride (SiON:H) could be used as a passivation layer, especially on the back side of the cell. In this work, it were deposited on crystalline silicon substrates by medium frequency magnetron sputtering from Ar+N2 + H2O, Ar + NH3 + H2O, gas mixtures with changed the operation current. The SiON:H layer was characterized by n&k measurements, Fourier Transformed Infrared Spectroscopy (FTIR) to determine film thickness and refractive index, Si-O, Si-H and N-H peak position. Minority carrier lifetimes were measured by the microwave photoconductance decay method (μ-PCD) before and after thermal annealing. It has been found that the method was possible to modify the refractive index (from 1.46 to 1.64) and increase the Minority carrier lifetimes after annealing at temperatures of 400°C, but decrease after annealing at temperatures of 600°C.