Photoluminescence mechanism of porous silicon has been studied and discussed for many years

a lot of academic models to explain this phenomenon were proposed.Each model can interpret certain experimental results

but can’t explain others or even can be contradictious

so it is debated and studied to date.The substrates used in this work were all ptype Si wafer with resistivity between 8～13Ω·cm and(111) crystalline orientation.The samples were prepared by anodic etching method in doublecell.The anodic etching was carried out in a solution of HF and ethanol at constant current density and at room temperature.Specimens were prepared under different conditions of current density

solution concentration and erosion time.Photoluminescence spectra of the samples have mostly four peaks:Peak 1:(660±5)nm;Peak 2:(690±10)nm;Peak 3:(740±5)nm and Peak 4:(775±5)nm.Energy positions corresponding to peak wavelength are:(1.88±0.02)eV;(1.796±0.03)eV;(1.675±0.01)eV and(1.599±0.01)eV respectively.The energy range is 1.6～1.9eV.Relation between preparation conditions and peak wavelength and intensity is set out.The peak wavelength shifts in a little range

but the intensity changes greatly with the difference of preparation conditions

so whole peak position shifts and full width at half maximum changes obviously.Relation between aging time and peak wavelength and intensity is set out also.With aging time

three main peak position changes less

some shift to the blue and some are almost immobile and others shift to the red

but the peak intensity weaken more and more.Different preparation conditions can generate different microcosmic structure

porous silicon with different structure perhaps has more different optical properties and photoluminescence properties.Structure and photo-luminescence properties of prepared porous silicon can change with the process of preservation.Experimental results suggest that photoluminescence of porous silicon is a result of multiple photoluminescence mechanism operating together; size distribution in a certain range not only influence on the bandwidth

but also is one of reasons inducing multipeak phenomenon.Structure characteristics of porous silicon determine its photoluminescence properties.