In this study, we report on the passivation quality of atomic layer deposition grown ultra-thin Al2O3 and Al2O3 capped with plasma-enhanced chemical vapor deposition deposited SiNx on Cz p-type wafers for the rear side of a passivated emitter and rear cell (PERC). Different activation recipes using N2, forming gas (FG), and two-step annealing for different durations are investigated before SiNx deposition. The effect of different Al2O3 thicknesses and corresponding activation processes on the Al2O3/SiNx passivation performance, after a high temperature firing step, is studied to reach a new optimization toward higher efficiency and lower cost. A record high iVoc of 720 mV is obtained after firing step from Al2O3/SiNx stacks with Al2O3 thickness as thin as ∼2 nm with FG annealing. Our results demonstrate that, under well-optimized process conditions, ultra-thin Al2O3 thicknesses provide superior passivation quality as compared to the larger thicknesses which are commonly applied in the PERC industrial line and the potential for further improvement of industrial PERC solar cells in terms of cost reduction and efficiency.
Ultra-thin Al2O3 capped with SiNx enabling implied open-circuit voltage reaching 720 mV on industrial p-type Cz c-Si wafers for passivated emitter and rear solar cells
Gamze Kökbudak, Ahmet E. Keçeci, Hisham Nasser, Raşit Turan; Ultra-thin Al2O3 capped with SiNx enabling implied open-circuit voltage reaching 720 mV on industrial p-type Cz c-Si wafers for passivated emitter and rear solar cells. J. Vac. Sci. Technol. A 1 January 2021; 39 (1): 012409. https://doi.org/10.1116/6.0000692
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