Approach for Al2O3 rear surface passivation of industrial p‐type Si PERC above 19%

Abstract

ABSTRACTAtomic layer deposition (ALD) of thin Al2O3 (≤10 nm) films is used to improve the rear surface passivation of large‐area screen‐printed p‐type Si passivated emitter and rear cells (PERC). A blister‐free stack of Al2O3/SiOx/SiNx is developed, leading to an improved back reflection and a rear recombination current (J0,rear) of 92 ± 6 fA/cm2. The Al2O3/SiOx/SiNx stack is blister‐free if a 700°C anneal in N2 is performed after the Al2O3 deposition and prior to the SiOx/SiNx capping. A clear relationship between blistering density and lower open‐circuit voltage (VOC) due to increased rear contacting area is shown. In case of the blister‐free Al2O3/SiOx/SiNx rear surface passivation stack, an average cell efficiency of 19.0% is reached and independently confirmed by FhG‐ISE CalLab. Compared with SiOx/SiNx‐passivated PERC, there is an obvious gain in VOC and short‐circuit current (JSC) of 5 mV and 0.2 mA/cm2, respectively, thanks to improved rear surface passivation and rear internal reflection. Copyright © 2012 John Wiley & Sons, Ltd.