Integration of Al2O3 as front and rear surface passivation for large-area screen-printed p-type Si PERC

Abstract

Atomic layer deposition (ALD) of thin Al2O3 (<= 10 nm) films is used to improve both front and rear surface passivation of large-area screen-printed p-type CZ Si passivated emitter and rear cells (PERC). As emitter passivation, the SiNx anti reflection coating (ARC) is capped with Al2O3, giving improved hydrogenation during co-firing and a front recombination current (J(0,front)) of 128 +/- 5 fA/cm(2). As rear surface passivation, a blister-free stack of Al2O3/SiOx/SiNx is employed, leading to optimal back reflection and a rear recombination current (J(0,rear)) of 92 +/- 6 fA/cm(2). Internal quantum efficiency (IQE) measurements clearly confirm the improved passivation properties of both Al2O3-based stacks, even compared to passivation stacks based on thermally grown SiO2. (C) 2012 Published by Elsevier Ltd. Selection and peer-review under responsibility of the scientific committee of the SiliconPV 2012 conference.