CRYSTALLITE-SIZE-DEPENDENT CHARACTERISTICS OF POROUS SILICON

Porous silicon prepared with anodic currents of 5 to 30 mA/cm(2) are c haracterized for structural and electronic properties of surface using photoluminescence, grazing angle X-ray diffraction, photoconductivity , thermally stimulated exo electron emission and work function measure ments. The observed results indicate that with increasing porosity the crystallite size decreases and the amount of silicon hydride and oxid e-type species increases, exhibiting a tendency similar to that of hyd rogenated amorphous silicon and hydrogenated microcrystalline silicon. Free-standing powder of porous silicon, characterized by bright photo luminescence at 730 nm, showed crystallites of nanometre dimensions un der the transmission electron microscope.