Atomic-layer deposited passivation schemes for c-Si solar cells

A review of recent developments in the field of passivation of c-Si surfaces is presented, with a particular focus on materials that can be prepared by atomic layer deposition (ALD). Besides Al₂O₃, various other novel passivation schemes have recently been developed, such as Ga₂O₃, Ta₂O₅, SiO₂/Al₂O₃, HfO₂/Al₂O₃ and TiO₂, which altogether can passivate a wider variety of doped and textured Si surfaces. Moreover, they are interesting candidates in the emerging field of passivating contacts, for instance as novel tunnel oxides. In this field, ALD can offer some distinct advantages, such as a precise control in film thickness, composition and even area-selective deposition.