LASER-INDUCED OXYGEN-ADSORPTION AND INTENSITY DEGRADATION OF POROUS SI

For light-emitting porous Si there has been a severe problem with instability and degradation in the light emission. We performed in situ photoluminescence measurements to monitor the degradation process under ambient atmosphere of different gases and in ultrahigh-vacuum environment. We found that laser induced oxygen adsorption is the major cause for the light emission degradation, while the laser heating effect can be excluded. We also found the degraded intensity can be partially recovered by reducing the surface oxygen concentration.