Mesoscale silicon pillars are formed when silicon wafers are irradiated by a nanosecond excimer laser operating at 308 nm and incident fluence of similar to3 J cm(-2). The morphology of the pillars responds to the chemical composition of the gas phase above the Si surface. Postprocessing can also be used to change the structure of the pillars. We demonstrate using Raman spectroscopy that the,pillars can be covered with a,nanocrystalline porous layer as the result of chemical etching. A stain etchant produces brilliant reddish-orange photoluminescent films. Porous pillars of this type are interesting candidates for use as drug and DNA delivery vehicles. (C) 2004 American Vacuum Society.