Spectroscopic study of red light emission in porous silicon

Since bulk silicon does not emit light in the visible part of the spectrum, the discovery of visible luminescence from porous silicon has been quite surprising and has generated significant interest. This material differs from bulk silicon in one important way, in that it consists of interconnected silicon nanostructures, having very large surface to volume ratios. The first emission mechanism proposed involved carrier recombination within quantum size silicon particles, but more recent work has shown that surface emission models may be more likely. The problems with the quantum confinement model will be discussed in view of current data, and an oxygen center luminescence model will be discussed, with supporting experimental data. A direct correlation between the presence of these centers and the red photoluminescence in both as-made and oxidized PSi will be presented.