Integration of Al2O3 as Front and Rear Surface Passivation for Large-Area Screen-Printed P-Type Si PERC

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 (J0,front) of 128 ± 5 fA/cm2. As rear surface passivation, a blister-free stack of Al2O3/SiOx/SiNx is employed, leading to optimal back reflection and a rear recombination current (J0,rear) of 92 ± 6 fA/cm2. 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.