Effect of Preparation Parameters on Physical, Thermal and Optical Properties of n-type Porous Silicon

Porous silicon (PSi) layers were formed on n-type silicon (Si) wafers using electrochemical etching method. The effects of etching time and current density were investigated. Three sets of samples were prepared at different current densities: 10, 20, and 30 mA/cm(2) and six etching times: 10, 20, 30, 40, 50, and 60 min. The thickness and porosity of the layers were measured using the gravimetric method. The surface morphology was studied by Field Emission Scanning Electron Microscope (FESEM). The optical and thermal properties of porous silicon on silicon substrates were investigated by employing photoluminescence (PL) and photoacoustic spectroscopy (PAS). Thermal results showed that the thermal diffusivity (TD) of samples decrease with increasing the porosity. The band gap of the samples were obtained from photoluminescence (PL) and photoacoustic absorption spectra. These results showed that the band gap of porous silicon samples increase with increasing porosity.