Effect of Fabrication Conditions and Aging Time on Photoluminescence of Porous Silicon
多孔硅PL谱的影响因素分析

Samples of porous silicon are fabricated by an electrochemical approach and photoluminescent properties of PS are studied systematically.It is found that,with the incresing of the current density,anodizing time and HF concentration in etching solution,the peaks of PL occures the blue shift,as well as intensity for peaks is enhanced.But excessive current density,anodizing time or HF concentration would bring the decrease of PL intensity.The results also shows that PL spectra have a multi peak structure.When PS are exposed to the air,the oxidation of PS would cause both blue shift of position and degradation of intensity for the peaks with short photoluminescent wavelength,and only cause a great deal decrease of the intensity of the long wavelength peaks.The multi peak structure of PL spectra might be interpreted by PS samples comprising two different microstructures,branched and spongy structures.The branched PS is related to the peaks at short wavelength and spongy PS is corresponded to peaks at long wavelength.And branched PS is oxidized more easily than spongy one when they are exposed to the air.All the above phenomena could be understood in the quantum confinement and luminescence center model.