Electroluminescence with high and stable quantum efficiency and low threshold voltage from anodically oxidized thin porous silicon diode

Highly efficient electroluminescence (EL) is obtained at low operating volt age (< 5 V) from n(+)-type silicon-electrochemically oxidized thin porous s ilicon-indium-tin-oxide junctions. Continuous wave external quantum efficie ncy greater than 1% and power efficiency of 0.37% have been achieved. Consi derable reduction of leakage current accounts for the enhancement of EL eff iciency upon oxidation. The EL time response (approximate to 30 mu s) is sl ower than the photoluminescence one, due to slow electrical charging of por ous silicon. No degradation of quantum efficiency is observed during operat ion and upon aging. This is attributed to the electrochemically grown oxide , which should provide a better surface passivation than the initial hydrog en coverage. (C) 2000 American Institute of Physics. [S0021-8979(00)01020-3 ].