Electrochemical Preparation And Photoluminescence Of Porous Silicon

The study of porous silicon mainly concentrated in enhancing the photoluminescence intensity and stability of porous silicon. In this paper,porous silicon samples were prepared by anodic etching method.The effects of preparation conditions was discussed. Meanwhile the influence of post-treatment was also discussed by using acid treatment and cathodic reduction treatment. Experiments showed that, for a fixed concentration and corrosion time, with the increase of current density,the photoluminescence intensity of porous silicon increased first and then decayed. This showed that there existed optimum corrosion current density to prepare porous silicon.When the solution was V(HF):V(C2H5OH)=1:1 and the corrosion time was 15min, the ideal corrosion current density would be 50 mA/cm2. For the same corrosion time and current density, with the increase of solution concentration, the photoluminescence intensity increased first and then decayed.This showed that there existed optimum solution concentration to prepare porous silicon. When the current density was 50mA/cm2, and the corrosion time was 15min, ideal solution would be V(HF):V(C2H5OH)= 1:3. For the same solution concentration and current density, with the increase of time, photoluminescence intensity increased first and then decayed. This showed that there existed optimum corrosion current density to prepare porous silicon. When solution was V(HF):V(C2H5OH)= 1:1 and current density was 10 mA/cm2, the optimum corrosion time would be 15min.It was found that, with the different experimental conditions, the photoluminescence peak of porous silicon had "red shift "or "blue shift ", it may due to surface states of porous silicon. When samples stored in the air, its photoluminescence intensity decayed, but for the samples with post-treatment, its stability of photoluminescence was much better. The data and phenomenon obtained by experiment could be explained by quantum wire model and luminescence center model. However, the surface states was also closely related to photoluminescence of porous silicon. There existed optimum conditions to prepare porous silicon;with different conditions, samples had different photoluminescence intensity and peak.