Surface passivation of high‐efficiency silicon solar cells by atomic‐layer‐deposited Al2O3

Abstract Atomic‐layer‐deposited aluminium oxide (Al2O3) is applied as rear‐surface‐passivating dielectric layer to passivated emitter and rear cell (PERC)‐type crystalline silicon (c‐Si) solar cells. The excellent passivation of low‐resistivityp‐type silicon by the negative‐charge‐dielectric Al2O3is confirmed on the device level by an independently confirmed energy conversion efficiency of 20·6%. The best results are obtained for a stack consisting of a 30 nm Al2O3film covered by a 200 nm plasma‐enhanced‐chemical‐vapour‐deposited silicon oxide (SiOx) layer, resulting in a rear surface recombination velocity (SRV) of 70 cm/s. Comparable results are obtained for a 130 nm single‐layer of Al2O3, resulting in a rear SRV of 90 cm/s. Copyright © 2008 John Wiley & Sons, Ltd.