Optical characteristics of porous silicon structures

Morphology, composition, and optical properties of porous silicon on single-crystal-silicon substrates and $p$–$n$ junctions are studied. Substrate orientation, type of conduction, and composition of etching agent are varied to obtain nano-, meso-, and microporous silicon and multilayer porous structures. A correlation of the photoluminescence intensity and intensity of the IR absorption band peaking at 616 cm$^{-1}$ is related to the presence of Si–Si bonds.