  Porous silicon layers (PS) have been prepared in this work via
Photoelectrochemical etching process (PEC) of n type silicon wafer of 0.8
ohm.cm resistivity in hydrofluoric (HF) acid of 24.5 precent concentration at
different etching times (5 to 25 min.). The irradiation has been achieved using
Tungsten lamp with different wavelengths (450 nm, 535 nm and 700 nm). The
morphological properties of these layers such as surface morphology, Porosity,
layer thickness, and also the etching rate have been investigated using optical
microscopy and the gravimetric method.
