Blue and green electroluminescence from a porous silicon device
The fabrication and the characteristics of light emitting porous silicon devices are presented. Under the influence of UV illumination during anodization a nanoporous layer on n-substrate is formed. The wafer shows weak photoluminescence with a maximum at 640nm. The porous layer is contacted by pads consisting of semitransparent gold. When voltage is applied, electroluminescence in the 560 to 480nm range can be observed. The current-voltage characteristic is strongly rectifying. Light emission occurs under forward bias. A possible model for the shift of the electroluminescence towards higher energies is given.