Study of Morphological and Optical Properties of Porous Silicon

Porous silicon layers have been prepared from non-polished p-type silicon wafers of (100) orientation. Scanning electron microscopy and fluorescence spectroscopy have been used to characterize the morphological and optical properties of porous silicon. The influence of varying the anodizing current density on the morphological and optical properties of porous silicon has been investigated. SEM micrographs show that by increasing the anodizing current density in the electrochemical process two peculiar surface morphologies are obtained. The surface morphology in the central region of the sample consists of solid cells delimited by trenches and the trenches bottom is covered by polyhedral pores, and the surface morphology in the periphery contains polyhedral and current-line-oriented pores. The fluorescence spectrum peak at the anodizing current density of 93 mA/cm² gets the maximum intensity and is blue shifted.