The Effect of Al Concentration in The Window Layer on the Efficiency of p- Ga1-xAlxAs/p-n GaAs Solar Cell

In this research a theoretical method was introduced to calculate the efficiency of GaAs solar cell, with a window layer (which epitaxially grown to prevent the surface recombination process caused by surface defects) which contains Al and the effect of variation of Al concentration on the efficiency of the solar cell, where we consider the window layer as a forth layer in the energy band diagram for the photovoltaic cell. Because of the lack of information about the necessary and essential variables for calculating the efficiency like absorption coefficient, effective mass of carriers, refractive index, ..etc. This variables was calculated by numerical methods using the few existing experimental information's. Absorption coefficient, refractive index, permittivity, coefficient and diffusion lengths and relaxation times for Al concentrations (0 45 %) and for the effective wavelengths were calculated and used to find the efficiency at the former Al concentrations.