Defect State Analysis in Ion-Irradiated Amorphous-Silicon Heterojunctions by HAXPES

The efficiency in HIT (heterojunction with intrinsic thin film) solar cells strongly depends on the passivation of dangling bonds at the a-Si:H/c-Si interface by hydrogen, introduced during the plasma-enhanced CVD process. Herein, controlled defects that are introduced by Ar ion irradiation have been studied. It has been observed by hard X-ray photoemission spectroscopy (HAXPES) that during Ar ion implantation, Si–H bonds in the a-Si:H layer are broken and become dangling bonds. The number of dangling bonds in the a-Si:H layer has been quantified, and the electronic states associated to them have been identified, which explains previously observed photoluminescence transitions.