Enhancement of electron selectivity of Si/TiO2 heterojunction via oxygen vacancies for carrier selective solar cell application

Titanium dioxide is widely used as an electron selective layer for silicon based carrier selective solar cells. For efficient carrier collection, the TiO2 film should passivate the Si surface, while maintaining its selective nature – which requires careful optimization of process conditions. Here, we compare the properties of TiO2 films deposited by plasma and thermal Atomic Layer Deposition (ALD). We observe that the films deposited without plasma are indeed more oxygen deficient, but interestingly provide better passivation of the silicon surface as compared to plasma assisted deposition process and have better electrical performance.