Effect of photo chemical etching and electro chemical etching on the topography of porous silicon wafers surfaces

In This research we study the effect of photo chemical etching and electrochemical etching on topography of porous silicon surfaces, the results showed that photo chemical etching produced roughness silicon layer which can have thickness be less of porous silicon layer which is produced by electro chemical etching When all the wafers have same etching time  and hydrofluoric solution (HF) concentration, the wafers have same resistance (10 Ω.cm). Also the results showed the roughness of porous silicon layers produced  by  electro chemical method which is bigger than the roughness of porous silicon layers produced by photo chemical method and the results of roughness of porous silicon layers, Pore diameter and porous layer thickness were produced by electro chemical method (1.55(µm) ((0.99(µm)) and ((1.21(µm) respectively), the results of roughness of porous silicon layers, Pore diameter and porous layer thickness were produced by photo chemical method 0.63)) nm -1.55)) (µm) ),so the (84.9 (nm)- and (3.94(nm) respectively . This is reinforces because of using the electro chemical to etching the wafer surf ace of bulk silicon and changing it to roughness silicon surface  be share in success of many practicalities.