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 Al
2
O
3
, various other novel passivation schemes have recently been developed, such as Ga
2
O
3
, Ta
2
O
5
, SiO
2
/Al
2
O
3
, HfO
2
/Al
2
O
3
and TiO
2
, 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.