Origin of the tunable carrier selectivity of atomic-layer-deposited Ti0x nanolayers in crystalline silicone solar cells

image illustrating the contrast between e contact and h contact

Dr Sebastian Ruy Bonilla and researchers from the Fraunhofer ISE, AIST in Japan and the National Renewable Energy Laboratory used Titanium oxide (TiOx) nanolayers grown by atomic layer deposition as carrier contacts for crystalline silicon (c-Si) cells.

This paper reveals how TiOx layers can be widely tunable from electron to hold selective depending on deposition conditions, post-deposition treatments and work function of the metal electrode used.

The experiements using TiOx demonstrated that carrier selectivity is correlated with the amount of c-Si band bending induced by TiOx, which are governed by the effective work function difference at the Si/TiOx interface and also by the negative fixed charge present in the TiOx layer.

This new finding highlights the influence of induced band bending to produce carrier depletion/inversion conditions, and the importance of its selectivity effect in a c-Si absorber.