Investigation of Porous Silicon Layers Properties Using Speckle Techniques for Photovoltaic Applications

Speckle imaging technique (SIT) is used as non-destructive testing to obtain indicative speckle patterns with the aim to be applied for photovoltaic solar cells. These speckle patterns are mainly characterized by their contrast and optical density (OD), which give indications for the properties of the solar cell. In the current work, the porous silicon layers (PSLs) acting as an anti-reflection coating (ARC) formed with different surface porosities are prepared on n(+)p textured crystalline CZ- silicon by electrochemical etching (ECE) in HF-based electrolyte using different current densities. The morphological properties of the PSLs are investigated by scanning electron microscopy (SEM). The optical properties of the textured surfaces are studied using photoluminescence PL and reflectivity measurements. The band gap energy of the prepared PSLs increases to 1.89 eV. The reflectivity of the PSLs decreases to 0.75% in a wavelength range (350-750) nm. The current-voltage (I-V) characteristics of Ag/PS/n + p/Ag junction are investigated which reveal an increment in the resulting short-circuit current density and the open-circuit voltage up to 2.96 mA/cm(2)and 0.385 V, respectively. These results show an improvement in the fill factor by 48.5%. The inspected properties of the porous silicon solar cells exhibit a correlation with the contrast and the OD of the speckle patterns imaged from these cells.