POROUS SILICON FORMATION - MORPHOLOGICAL STABILITY ANALYSIS

Morphological stability analysis for the photoelectrochemical etching of n-type Si is performed, in which the stability of the back-illumina ted Si-electrolyte interface is theoretically investigated. Both the t ransport of holes in the semiconductor and ions in the diffusion layer are considered, together with the electrochemical reaction and surfac e energy. The roles and the effects of the various parameters, such as applied voltage, dopant concentration, current density, illumination intensity, surface energy, and electrolyte concentration, on the morph ology of porous silicon are studied. The results show that porous sili con is formed when the dissolution process is controlled by the supply of holes in the semiconductor, and the density of porous silicon is b oth material- and process-dependent.