(Invited) Blue Phosphorescence in Oxidized Nano-Porous Silicon

Abstract

Heavily oxidized porous silicon treated by high-pressure water vapor annealing exhibits a strong blue light emission band which includes a long-lived phosphorescence (Ph) component. This Ph is particularly strong below 200 K. Above 200 K, it experiences a progressive thermally activated quenching. The intensity of the Ph and the peak of its spectrum depend on the excitation energy, and a large Stokes shift was observed. The Ph spectrum included six components exhibiting similar optical properties and likely due to vibronic features of molecular-like species. The Ph was modeled as the result of recombinations from triplet states to ground levels. Its origin is related to silicon nanostructures in an oxide matrix.