Nanostructured silicon

Nanostructured silicon (porous-Si, Si nanocrystals in SiO2, Si nanowires etc., see the Library) raised a wave of scientific activity in 1990 as the promising material for silicon based optoelectronics.

The kinetics of the phosphorescence decay of a porous silicon in a wide temperature range is anomalously slow (the integral over the extrapolated signal diverges). This phenomena is observed in some conjugated polymers, but the existing explanation as the tunneling recombination of geminate electron-hole pairs requires an unnatural distribution of activation energies for porous silicon: wide, flat, with depression at small energies.


In my PhD thesis I demonstrate that this is a generic feature of disordered systems with significant initial separation of the recombining particles: it is their multiple retrapping which is responsible for the depression of the distribution of activation energies.