Origin of the photoluminescence shifts in porous silicon

Abstract

The origin of the photoluminescence (PL) shifts in Porous Silicon (PS) is discussed according to a quantum confinement - based model, in which we modelize the PS layer as a mixture of quantum dots and wires. It was shown that a PL blueshift or redshift may occur during laser irradiation of PS, depending on preparation conditions. No PL shift was observed for some PS samples, even after a long ageing in air, due to the presence of an amorphous silicon phase detected from Raman spectroscopy measurements. It was found that the presence of the amorphous phase plays an important role in the PL behaviour of oxidised PS.