Excellent boron emitter passivation for high-efficiency Si wafer solar cells using AlOx/SiNx dielectric stacks deposited in an industrial inline plasma reactor

Abstract

Excellent passivation of boron emitters is realised using AlO x/SiNx dielectric stacks deposited in an industrial inline plasma-enhanced chemical vapour deposition reactor. Very low emitter saturation current density (J0e) values of 10 and 45 fA/cm2 are obtained for 180 and 30 Ω/sq planar p+ emitters, respectively. For textured p+ emitters, the J0e was found to be 1.5-2 times higher compared with planar emitters. The required thermal activation of the AlOx films is performed in a standard industrial fast-firing furnace, making the developed passivation stack industrially viable. We also show that an AlOx thickness of 5 nm in the AlOx/SiN x stack is sufficient for obtaining a J0e of 18 fA/cm 2 for planar 80 Ω/sq p+ emitters, which corresponds to a 1-sun open-circuit voltage limit of the solar cell of 736 mV at 25 °C. Copyright © 2012 John Wiley & Sons, Ltd.