Effect of ageing on the statical and time-resolved photoluminescence spectra of porous silicon

This paper reports on the ageing effect of porous silicon studied by statical and time-resolved photoluminescence spectroscopy. An increase in the full-width at half-maximum of the statical photoluminescence spectra of porous silicon from 200 meV to 500 meV after ageing of 24 hours in the air is observed and can be attributed to added emission mechanism via self-trapped electrons. The blue zone in the time-resolved photoluminescence spectra is found only after ageing of 72 hours in the air and the luminescence intensity of this zone increases by increasing the duration of the ageing. These results suggest that the intense and stable blue-light emission of porous silicon in the air may arise from defects in silicon oxide.