Approach for Al 2 O 3 rear surface passivation of industrial p‐type Si PERC above 19%

Atomic layer deposition (ALD) of thin Al 2 O 3 (≤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 Al 2 O 3 /SiO x /SiN x is developed, leading to an improved back reflection and a rear recombination current ( J 0,rear ) of 92 ± 6 fA/cm 2 . The Al 2 O 3 /SiO x /SiN x stack is blister‐free if a 700°C anneal in N 2 is performed after the Al 2 O 3 deposition and prior to the SiO x /SiN x capping. A clear relationship between blistering density and lower open‐circuit voltage ( V OC ) due to increased rear contacting area is shown. In case of the blister‐free Al 2 O 3 /SiO x /SiN x rear surface passivation stack, an average cell efficiency of 19.0% is reached and independently confirmed by FhG‐ISE CalLab. Compared with SiO x /SiN x ‐passivated PERC, there is an obvious gain in V OC and short‐circuit current ( J SC ) of 5 mV and 0.2 mA/cm 2 , respectively, thanks to improved rear surface passivation and rear internal reflection. Copyright © 2012 John Wiley & Sons, Ltd.