Electrochemical etching was carried out to produce porous silicon based on crystalline silicon n-type (100) and (111) wafers. Etching times of 10, 20, and 30 min were applied. Porous silicon layer was used as anti-reflection coating on crystalline silicon solar cells. The optimal etching time is 20 min for preparing porous silicon layers based on crystalline silicon n-type (100) and (111) wafers. Nanopores with high porosity were produced on the porous silicon layer based on crystalline silicon n-type (100) and (111) wafers with average diameters of 5.7 and 5.8 nm, respectively. Average crystallite sizes for the porous silicon layer based on crystalline silicon n-type (100) and (111) wafers were 20.57 and 17.45 nm at 20 and 30 min, respectively, due to the increase in broadening of the full width at half maximum. Photoluminescence peaks for porous silicon layers based on crystalline silicon n-type (100) and (111) wafers increased with growing porosity and a great blue shift in luminescence. The minimum effective coefficient of reflection was obtained from porous silicon layers based on the crystalline silicon n-type (100) wafer compared with n-type (111) wafer and as-grown at different etching times. Porous silicon layers based on the crystalline silicon n-type (100) wafer at 20 min etching time exhibited excellent light trapping at wavelengths ranging from 400 to 1000 nm. Thus, fabricated crystalline silicon solar cells based on porous silicon (100) anti-reflection coating layers achieved the highest efficiency at 15.50% compared to porous silicon (111) anti-reflection coating layers. The efficiency is characterized applying I-V characterization system under 100 mW/cm2 illumination conditions.
Fabrication and Characterization of Porous Silicon Layer Prepared by Photo-Electrochemical Etching in CH3OH:HF Solution
