Study of the photoluminescence instability of porous silicon under light illumination

The profile of photoluminescence instability in porous silicon as a function of time under light illumination was studied. Three stages with different characteristic time scales were identified in the evolution curve. In the first stage, the photoluminescence intensity decays very fast, the second stage is an enhancement process, and finally another slowly decaying stage dominates. A striking behavior was also observed in the evolution profile, which shows that the enhancement stage changes to a decay process when the illumination intensity is increased. With the study of the dependence on the illumination intensity, a qualitative model has been suggested to explain our observations. The effect of oxygen on each evolution stage was also investigated. It gives valuable information about the microscopic structures of porous silicon. Copyright (C) 1996 Elsevier Science Ltd