Simulation of Optical Properties of the Si/SiO2/Al Interface  at the Rear of Industrially Fabricated Si Solar Cells

Y. Yang[1], and P. Altermatt[1,2]
[1]Institute for Solar Energy Research Hamelin (ISFH), Emmerthal, Germany
[2]Dep. Solar Energy Research, Inst. Solid-State Physics, Leibniz University of Hanover, Germany

The specular and diffuse reflection properties of sunlight at the rear surface of silicon solar cells with various degrees of roughness are computed by solving the Maxwell and material equations in two dimensions, using the COMSOL RF Module. The model is tested on planar Si/SiO2/air interfaces and planar Si/SiO2/Al interfaces.

The simulations show that for wavelengths of 800 nm, (i) maximum scattering is achieved with a standard deviation for roughness between 50 nm and 100 nm, (ii) the distribution probabilities for scattering are similar if roughness is produced by etching solely the grown SiO2 instead of the Si. Output parameters for geometrical ray tracers are computed.