Behind the Nature of Titanium Oxide Excellent Surface Passivation and Carrier Selectivity of c-Si

摘要

We present an expanded study of the passivation properties of titanium dioxide (TiO) on p-type crystalline silicon (c-Si). We report a low surface recombination velocity (16 cm/s) for TiO passivation layers with a thin tunnelling oxide interlayer (SiO or AlO) on p-type crystalline silicon (c-Si). The TiO films were deposited by thermal atomic layer deposition (ALD) at temperatures in the range of 80-300  ̊C using titanium tetrachloride (TiCl) as Ti precursor and water as the oxidant. The influence of TiO thickness (5, 10, 20 nm), presence of additional tunneling interlayer (SiO or AlO), and post-deposition annealing temperature were investigated.We have observed that that SiO and AlO interlayers enhance the TiO passivation of c-Si. TiO2 thin film passivation layers alone result in lower effective carrier lifetime. Further annealing at 200  ̊C in N gas enhances the surface passivation quality of TiO tremendously.