Reflectance of Sub-Wavelength Structure on Silicon Nitride for Solar Cell Application

In this study, reflection properties of sub-wavelength structures (SWS) on silicon nitride (Si₃N₄) antireflective coatings are investigated. Numerical calculation of SWS reflection based on a rigorous coupled-wave approach is conducted and compared with the measurement of fabricated samples. We compare the results of single and double-layer-antireflection (SLAR and DLAR) coatings with SWS on Si₃N₄, taking into account average residual reflectivity over a range of wavelengths, where the solar efficiency is further estimated. A low average residual reflectivity of 9.56% could be obtained for a Si₃N₄ SWS height and nonetched layer of 140 nm and 60 nm respectively, which will be less than 80 nm Si3N4 SLAR (~15%) and almost the same as that of a DLAR with 60 nm Si₃N₄ and 70 nm magnesium fluoride (~10%).