Photo- and electroluminescence from electrochemically polished silicon

Visible photoluminescence has been obtained from surface-etched silicon fabricated with high-current-density anodization on the order of 1000 mA/cm 2 (electrochemical polishing mode). Anodization at this current density makes silicon mirror-like with blue or yellow color. Photoluminescence intensity is almost equal to that of porous Si even for a thin layer on the order of a nanometer. Using such a layer, we have fabricated light-emitting diodes by indium tin oxide evaporation. Schottky-type junctions formed in this way have a large rectifying ratio on the order of 10 4 at ±15 V and show visible electroluminescence at a threshold bias voltage of less than 5 V.