Evidence of the Nano-sized Si Microstructure of Porous Si FromScanning Tunneling Microscopy

Scanning tunneling microscopy was used to observe the morphological feature of luminescent porous Si Results show that the surface of porous Si consists of randomly distributed nano-sized Si grains, which may be Si clusters. No clear interface was found between the grains. Its microstructure looks like a sponge. Visible photoluminescence in porous Si is most likely due to the carrier confinement in this microstructure.