Photoinduced hydrogen loss from porous silicon

In this letter we show that UV illumination of porous silicon causes a decrease in its luminescence efficiency. Infrared measurements allow us to associate the efficiency decrease with a loss of hydrogen from the silicon surface. We also find that the rate at which the luminescence intensity degrades increases rapidly when the illumination energy exceeds a threshold near 3.0 eV. We conclude that the decrease in photoluminescence efficiency occurs as a result of optically induced hydrogen desorption and discuss possible explanations for the energy threshold.