Effect of illumination wavelength and intensity on minority-carrier diffusion length of EFG silicon ribbon solar cells

Local spectral photoresponses of the edge-defined film-fed growth technique (EFG) ribbon solar cells were measured as a function of the bias light wavelength and intensity. The minority-carrier diffusion length estimated from the spectral response measurement of the short-circuit current (J
Sc
) was found to increase semilogarithmically with the intensity at various bias light wavelengths, and to increase with the bias fight wavelength for the constant intensity in the position with a medium diffusion length (≃20 µm). In the position with a longer (≃89 µm) or shorter (≃7 µm) diffusion length, the bias light wavelength, however, had a smaller influence on the diffusion length. The effect of the bias light wavelength and intensity on the diffusion length is theoretically explained by a model of filling deep traps by photo-injected minority carriers.