Effects of anodization conditions and types of crystalline silicon on photoluminescence of porous silicon

The dependence of room-temperature visible photoluminescence (PL) of porous silicon (PS) and its microstructure on the anodization conditions and conductivity types and the doping level of the substrate was studied systematically. The results showed that the increase of etching time and current density, and the decrease of HF concentration in etching solution resulted in a blue shift of luminescent wavelength and a complicated change of PL intensity of PS. The luminescence efficiency of n - PS (fabricated with lightly doped n - Si) was higher than that of n+ - PS, and the wavelength of the former was shorter. And conductivity types of the substrate had no distinct effect on the luminescence of PS. All the results were explained with the quantum confinement effect and the formation mechanism of PS.