To obtain high quality ZnO thin films for use as transparent electrodes of amorphous silicon solar cells, hydrogen treatment of the films using photo-chemical vapor deposition was performed for the first time. The as-deposited ZnO thin film was irradiated by UV light during the flow of hydrogen molecules in the presence of photo-sensitizers of mercury. As the treatment time increased, resistivity decreased from 1 × 10−2Ωcm to 2 × 10−3Ωcm. Moreover, haze ratio increased from 20% to 48%. Hydrogen radicals were thought to be playing various roles on the neighborhood of the surface region and the grain boundary region.
This new trial gave us new understanding into the relation between hydrogen and ZnO. Moreover, these results could be applied to the process of amorphous silicon solar cells and a possible increase of efficiency is expected.