Surface Passivation and Simulated Performance of Solar Cells With Al $_{\bf 2}$ O $_{\bf 3}$ /SiN

Al₂O₃/SiN_x stacks that are prepared at low temperatures in chemical vapor deposition processes excel in terms of surface passivation applicable in industrial p-type Si solar cells. The conversion efficiencies that are feasible for solar cells with Al ₂O₃/SiN_x rear dielectric stacks, have been investigated by numerical simulations, including the optical performance of the stacks, which was considered for various Al ₂O₃ and SiNx film thicknesses. The optically optimized film thicknesses were found to be 15-30 nm for Al₂O₃ and 100-120 nm for the SiN_x films. Experimentally, the surface passivation was found to be similar for annealed Al₂O₃/SiN_x stacks and single-layer Al₂O₃ films with an almost equal level of field-effect and chemical passivation, as determined by optical second harmonic generation and corona charging experiments.