Illumination effects on the physical properties of porous silicon prepared by PECE

Abstract

Laser-assisted etching process was used to prepare porous silicon on n-type silicon substrate of resistivity 10 Ω cm and orientation incubated in hydrofluoric acid of 25% concentration. The porous layers were prepared using laser diode of 645 nm wavelength illumination with different intensities of about 14 and 20 mW/cm2 and current density of 10 mA/cm2 for a fixed etching time (8 min). The morphology and optical characterization of porous silicon were evaluated. Scanning electron microscopy results demonstrated that the power density is a prominent parameter that controls the morphology of pores. The reflectivity decreased with increase in the highest power density to 0.66% and the peak position of PL results increased with increase in power density and moved toward the blue region. These phenomena were due to changing in the characteristics of the surface morphology the change of Si to nanostructures.