Parameterization of Free Carrier Absorption in Highly Doped Silicon for Solar Cells

Free carrier absorption (FCA) is a parasitic absorption process in highly doped silicon that might significantly reduce the amount of photons, potentially generating electron-hole pairs. Existing FCA parameterizations are mostly setup by evaluating absorption data in the range λ ≥ 4 μm. If applied in the wavelength range λ = 1.0-2.0 μm, including the relevant range for silicon solar cells, most parameterizations are not appropriate to describe FCA accurately. In this paper, new parameters are presented using optical simulation on the base of experimental reflection data to enhance the quantification of FCA losses in the considered wavelength range.