Porous silicon: Influence of etching temperature on microstructure and luminescence

Electrochemical etching in solutions based on hydrofluoric acid has been wi dely used to form light-emitting porous silicon. However, the effects of a number of the experimental parameters on the quality of the porous silicon produced have yet to be fully investigated. In the present paper the influe nce of temperature and viscosity of the etching solution is evaluated in te rms of the morphology and porosity of the porous silicon produced as well a s the wavelength of the photoluminescence or electroluminescence subsequent ly emitted. It was found that under stimulation from a UV light source the wavelength of the photoluminescence emitted from the porous silicon films b lueshifted with decreasing etching temperature. SEM and AFM investigations revealed that this blueshifting of the photoluminescence resulted from the production of smaller nanocrystals at the lower etching temperatures.