1. Porous Silicon: a novel nanomaterial By Suchitra Ramani ECEN, OSU

2. Discovered at Bell labs by Uhlir in 1956 Two methods:1)Electrochemical anodization of bulk Si (p/n type) 2)Stain etching R. L. Smith and S. D. Collins, J. Appl. Phys. 71, R1 (1992) Porous Silicon: Fabrication Metal back contact HF + ethanol Si wafer +- HF resistant cell Pt cathode

3. Silicon sponge - Disordered nanostructure Large surface area ~ 600 m 2 /cm 3 Types: Microporous < 2nm Mesoporous (2 -50)nm Macroporous > 50nm Photoluminescence in the visible region : Eg~1.4 to 2eV PS layer porosity, thickness and morphology tailored with HF concentration, anodization time and current density Quantum confinement Ageing by exposure to ambient air Porous Silicon: Features Bernard Gauthier-Manuel and Tristan Pichonat

4. Current research and Potential applications Gas sensor Microcavity Broadband AR coating LED for THz Chemical Sensors Smart Dust Pressure Sensor Photonic crystal Biosensor for pathogen detection, detection of Toxins Drug delivery Georgia Inst. of Tech Univ. of Rochester Biosilicon TM