Effective silicon surface passivation by atomic layer deposited Al₂O₃/TiO₂ stacks

Abstract

Abstract In this work atomic layer deposition of Al 2 O 3 and TiO 2 has been used to obtain dielectric stacks for passivation of silicon surfaces. Our experiments on n‐ and p‐type silicon wafers deposited by thin Al 2 O 3 /TiO 2 stacks show that a considerably improved passivation is obtained compared to the Al 2 O 3 single layer. For Al 2 O 3 films thinner than 20 nm the emitter saturation current density decreases with increasing TiO 2 thickness. Especially the passivation of ultrathin (∼5 nm) Al 2 O 3 is very effectively enhanced by TiO 2 due to a decreased interface defect density as well as an increased fixed negative charge in the stacks. Hence, the thin Al 2 O 3 /TiO 2 stacks developed in this work can be used as a passivation coating for Si‐based solar cells. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)