STRUCTURAL AND PHOTOLUMINESCENCE PROPERTIES OF POROUS SILICON: EFFECT OF SURFACE PASSIVATION

The surface passivation of porous silicon is a determining factor in the emission efficiency of the material. The hydrogen surface coverage has been shown to provide very efficient passivation. In this work, we have monitored Si–Hn surface coverage, which is readily-obtained porous silicon formed at 1:3 concentrations of HF: ethanol with/without HCl content in the electrolytes, and relate it to the emission efficiency. SEM, FTIR and PL studies were carried out to understand the role of HCl content in the electrolytes. When samples are anodized with HCl content in the electrolytes, there is a net decrease in the concentration of the Si–H groups on the material surface. This treatment provokes desorption of the hydrogen atoms and results in a drastic decrease in the photoluminescence.