Unraveling the Influence of Hydrofluoric Concentration on the Morphology of Porous Silicon Surfaces Fabricated through Photochemical Etching using Sunlight

Abstract

Samples of n-type porous silicon samples with negative conductivity, low resistivity (4.3x10^-4 Ω.cm) and crystalline orientation (100) were prepared by photochemical etching method using sunlight as a light source. The intensity of the incident sunlight was collected and focused on the surface of the sample through a telephoto lens with a diameter of 7.5 cm and a focal length of 30 cm. The effect of changing concentrations of hydrofluoric acid (20%, 30%, and 40%) when using etching time of 30 min and illumination intensity of 6181 mW/cm² was studied. The results of surface morphology showed forming porous layers with thicknesses 527.7, 594.7, and 663.4nm and mean grain diameters of 104.9, 121.1, and 99.80 nm, respectively.