Absence of carrier recombination associated with the defect pool model in a-Si:H i-layers: Evidence from current-voltage characteristics on p-i-n and n-i-p solar cells

Forward bias current–voltage characteristics (JD–V) were studied for both p–i–n (superstrate) and n–i–p (substrate) (a-SiC:H p)/(a-Si:H i) solar-cell structures having different p/i interface layers and different thickness i-layers. Contributions of the p/i interfaces to the JD–V characteristics were separated, and the dependence on the thickness of the i-layers was established. Equivalence was observed in a comparison of the characteristics of p–i–n and n–i–p cells. The various JD–V characteristics are found to be consistent with uniform densities of defects in the i-layers, and thus inconsistent with the spatially varying large densities of defects predicted for solar-cell structures by the defect pool model.