Effect of oxygen annealing on spatial atomic layer deposited aluminum oxide/silicon interface and on passivated emitter and rear contact solar cell performance

Abstract In this study, aluminum oxide (Al 2 O 3 ) thin films are deposited via spatial atomic layer deposition on p-type silicon wafer. Then, a post-deposition annealing is performed in oxygen to activate the field-effect and chemical passivation. The annealing temperature is varied from 300 °C to 750 °C, and its effect on the structural properties and carrier lifetime of Al 2 O 3 /Si is investigated. The results show that at the annealing temperature of 600 °C, the highest minority carrier lifetime obtained is 446.5 μs and maximum surface recombination rate is 22.4 cm/s. Annealing temperatures higher than 600 °C lead to deteriorate surface passivation due to insufficient hydrogen passivation and structural change from AlO 4 to AlO 6 that cause low oxide fixed charge. Photovoltaic performance is simulated and compared with experimental results. The simulation shows that the p-type passivated emitter and rear contact (PERC) solar cell with the Al 2 O 3 single layer annealed at 600 °C can have open-circuit voltage (V oc ) of 678 mV and conversion efficiency (η) of 21.96%, while the PERC solar cell with SiN x :H/Al 2 O 3 doubled layer can achieve V oc of 679.7 mV and η of 22.03%, which is very close to the upper limit in the case of ideal rear passivation. The simulation is in a good agreement with the fabricated PERC solar cell showing V oc  = 679.2 mV and η = 21.6%.