Contact passivation in silicon solar cells using atomic-layer-deposited aluminum oxide layers

Atomic-layer-deposited aluminum oxide (AlO(x)) layers are implemented between the phosphorous-diffused n-emitter and the Al contact of passivated emitter and rear silicon solar cells. The increase in open-circuit voltage V(oc) of 12 mV for solar cells with the Al/AlO(x)/n(+)-Si tunnel contact compared to contacts without AlO(x) layer indicates contact passivation by the implemented AlO(x). For the optimal AlO(x) layer thickness of 0.24 nm we achieve an independently confirmed energy conversion efficiency of 21.7% and a V(oc) of 673 mV. For AlO(x) thicknesses larger than 0.24 nm the tunnel probability decreases, resulting in a larger series resistance. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim