Surface Passivation and Simulated Performance of Solar Cells With Al O /SiN Rear Dielectric Stacks

Al 2 O 3 /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 2 O 3 /SiN x rear dielectric stacks, have been investigated by numerical simulations, including the optical performance of the stacks, which was considered for various Al 2 O 3 and SiN x film thicknesses. The optically optimized film thicknesses were found to be 15-30 nm for Al 2 O 3 and 100-120 nm for the SiN x films. Experimentally, the surface passivation was found to be similar for annealed Al 2 O 3 /SiN x stacks and single-layer Al 2 O 3 films with an almost equal level of field-effect and chemical passivation, as determined by optical second harmonic generation and corona charging experiments.