Investigation of HF/H_2O_2 Concentration Effect on Structural and Antireflection Properties of Porous Silicon Prepared by Metal-Assisted Chemical Etching Process for Photovoltaic Applications

Porous silicon was successfully prepared using metal-assisted chemical etching method. The Effect of HF/H_2O_2 concentrations on the porosity type and size was investigated as an effective parameter in etching solution. Various structures can be synthesized by implementing different regimes of ρ which is the function of molar ratio of HF/H_2O-2. It is found that the best achieved etching rate is equal to 85%. Field Emission Electron Microscopy (FE-SEM) confirmed that all etched samples have porous structure and the sample which was immersed into HF/H_2O_2 with molar ratio of 7/3.53 has the smallest porosities. The average roughness of 288 nm and reflectivity as low as 7% could be achieved using this molar ratio. The Raman peak appeared at 520.09 cm^-1 confirmed that there weren’t any defect and stress in the porous structure. Current density-Voltage characterization was done for investigation important parameters of the prepared solar cells which had different structures. So it was shown that the porous sample immersed into HF/H_2O_2 with molar ratio of 7/3.53 had Jsc and Voc equal to 0.118Acm^-2 and 0.56V, respectively. The prepared porous silicon is a potential candidate for replacing antireflective layers in photovoltaic devices because of its low production cost, high antireflective property, and possibility of integration process relative to other antireflection layers.