Mechanism of red light emission in porous silicon

Although bulk silicon (Si) does not emit light in the visible part of the spectrum, porous silicon has been shown to emit light in the red. This material differs from bulk Si in one important way, that is, it consists of interconnected Si crystallites, having very large surface to volume ratios. The first emission mechanism proposed involved carrier recombination within quantum size Si 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.