White Light from an Indium Zinc Oxide/Porous Silicon Light-Emitting Diode

Stable white light electroluminescence from a light-emitting diode fabricated from porous silicon with a transparent indium zinc oxide (IZO) top contact layer is presented. High-resolution transmission electron microscopy shows that IZO deposition on porous silicon causes the formation of an amorphous interfacial layer, possibly the source of the additional blue light needed to convert the normally red/green electroluminescence to white. Although the exact cause of the blue emissions has not been identified, a number of possibilities are postulated. An alternative explanation based on junction breakdown is also discussed.