Effect of post-treatment processes on the photoluminescence of porous silicon

Photoluminescence (PL) of the porous silicon post treated in different processes has been investigated. It was found that the age of the PS samples in ambient air and in dry air could greatly enhance the intensity of PL band at 570 nm and appeared a new blue emission band. Furthermore, the water and ethanol could stabilize the long-wavelength emission and enhance the short-wavelength emission because the molecules of water and alcohol were adsorbed on the surface of PS samples, which change the defects in the silicon oxide on the surface of the samples. The thermal oxidation at low-temperature situation could form a thin and imperfect oxide layer on the surface of PS samples, which also change the defect types on the surface of PS samples and change the emission band. The metal ions could form the ion molecule complexes with species of the surface of PS samples so that the emission characteristics of the samples immersed in chloride salt solution changed.