Silicon heterojunction solar cells with high surface passivation quality realized using amorphous silicon oxide films with epitaxial phase

Abstract

The epitaxial growth of the i-layer of crystalline silicon heterojunction solar cells has been widely accepted as harmful to surface passivation. In our experiments, however, although a very rough epitaxial phase in the intrinsic a-Si1−xOx:H passivation layer was confirmed by transmission electron microscopy and spectroscopic ellipsometry, a high effective lifetime and an implied-VOC of over 720 mV were achieved with lifetime samples. The high passivation quality was confirmed by the obtained open circuit voltages of 728 and 721 mV for n- and p-type solar cells, respectively, with an a-Si1−xOx:H/p-µc-Si1−xOx:H stack rear structure. These results indicate that, contrary to the common knowledge, high surface passivation quality can be achieved even when the epitaxial phase is present.