PECVD nanocrystalline silicon films versus porous silicon: Structural and optical properties

A comparative experimental study is conducted of nanocrystalline-and porous-silicon films from the viewpoint of their structural, luminescent, and optical properties, the films being fabricated by PECVD and electrochemical etching, respectively. The x-ray-diffraction data obtained imply that the PECVD films consist of nanocrystals that are uniformly (004) oriented and measure on average 4.8 nm across. It is shown by an AFM investigation that the films have a very rough surface occupied by sharply pointed nanoscale asperities. The films can exhibit room-temperature photoluminescence that is strongest at a photon energy of 1.55 eV. Optical properties of the nanocrystalline-and porous-silicon films are examined in the visible range and the IR. The nanocrystalline-silicon films are found to have similar physical and chemical properties to the porous-silicon films. © Nauka/Interperiodica 2007.