Light trapping effect in silicon wafers with anodically etched surfaces

Spectral dependencies of the transmittivity and the photoresponse of silicon wafers one face of which was covered with a porous layer have been measured. These experiments had evidenced an increase of the light intensity absorbed in the wafer, which was largest at the wavelengths corresponding to the bandedge transitions. Experimental observations have been explained in terms of multiple light scattering inside the wafer caused by rough surface of the porous layer.