Antireflection of nano-sized SiO sphere arrays on crystalline silicon solar cells

Optical properties of dielectric nano-sized sphere, embedded sphere and hemisphere arrays on SiN coated Si texture wafer were studied using the three dimensional finite-difference time-domain method. These arrays increase the photon currents each with an appropriate radius range. The spheres with a radius of 60 nm shows the strongest enhancement at normal incidence. The spheres can be seen as an additional antireflection coating by effective medium theory, because the sphere radius is smaller than the wavelengths of AM1.5G spectrum. It also shows the properties of omnidirectional antireflection due to the coupling of light through nano-sized spheres into Si with oblique incidence. For the angle of incidence from 0^o to 75^o, the sphere arrays on SiN coated Si texture shows the lowest averaged weighted reflectance.