Light scattering coefficients for textured SnO

Transparent electrodes that are used in amorphous silicon solar cells are textured to provide light scattering. We studied the light scattering behavior in transmission and reflection and found that in order to describe the measured spectra thickness variations of 50–60 nm over several micrometers have to be assumed. This is in qualitative agreement with measured rms roughnesses as determined with atomic force microscopy (AFM). It is important to include these thickness variations in the modeling of amorphous silicon solar cells. The wavelength dependence of the light scattering in transmission at the TCO–air interface was found to be λ⁻³ for light incident from both sides. Scattering of the weakly absorbed long wavelength light at the back contact is therefore essential in order to obtain high solar cell efficiencies.