Atomic force microscopy 1 Catalyst selectivity 1 Crystallite size 1 Effective-mass theory Electrochemical etching 1 Electrolytes 1 Etching technique 1 Hydrofluoric acid 1 Optical characteristics 1 Photoluminescence 1 Photoluminescence peak 1 Photoluminescence spectrum 1 Porosity 1 Porous silicon 1 Porous silicon formation 1 Pulsed electrochemical etchings 1 Quantum confinement effects 1 Quantum theory 1