Double layered silicon nitride coated pyramid formation by etching on silicon substrate for photovoltaic application

Abstract

One of the most effective ways to decrease reflection losses, enhance the likelihood of light trapping, and boost light absorption is surface patterning of p-type monocrystalline Si(100). Monocrystalline silicon surfaces' reflectivity is significantly decreased by the surface texturing of pyramids. This study looked into and analyzed how much of a pyramid was produced on the top of p-type Si substrates when the etching parameters were altered during Si texturing. The light traps created by the pyramidal structures on the crystalline silicon surface improved the effectiveness of light absorption. The impact of pyramid size on percent reflectivity was examined, and it was found that the percent reflectance and pyramidal etching time had an inverse connection. The texturing procedure, which involved adjusting the amounts of sodium hydroxide (NaOH) and isopropyl alcohol (IPA), as well as the length of the etching process, were used to regulate the size of the pyramids. The optimal etching conditions in this study were found to be a solution made with 12 weight percent NaOH and 4 volume percent IPA at an etching temperature of 80 0 C and an etching period of 40 min for wet etching. Pyramid with etching time (40 min) are post-coated with single-and double-layered silicon nitride (Si3N4), their reflectivity is measured over wavelength of 380-850 nm, had the lowest average percent reflectance of the double-layered Si3N4 patterned Si surfaces, at 8.8%. The selection of the refractive index (n) and the thickness (t) for single (n=1.9, t=80 nm) and double layer (n=2.8 and t=38 nm for bottom layer and n=1.9, t=42 nm) Si3N4 was done according to the destructive interference condition satisfied i.e., minimum reflection for photovoltaic application.