High-Performance a-SiGe Solar Cells Using a Super Chamber Method

The influence of impurities on the a-SiGe film properties was investigated using a super chamber. It was found that a-SiGe films with a low impurity concentration can maintain a high photosensitivity of about 106 for Ge content up to 13%, and impurity incorporation deteriorates film rigidity, which was first deduced from the STM (scanning tunneling microscope) measurement. Using a super chamber method, the highest conversion efficiency of 3.34% was obtained for an a-SiGe single-junction cell under red light (long-wavelength light (>~650 nm) by filtering AM-1.5, 100 mW/cm2 light). A conversion efficiency of 11.9% was also achieved for a stacked cell of a-Si/a-Si/a-SiGe.