Light-induced electroluminescence of porous silicon layers on p-Si in persulfate solution

Electroluminescence has been observed using the photostimulated reduction of persulfate ions at porous silicon layers grown on p(-)-Si substrates. Electrons were generated in the substrate by illumination from the ohmic contact side. The detection of visible electroluminescence shows that photogenerated electrons accumulate in the porous layer when the p(-) substrate is reverse biased. Voltage tuning of the electroluminescence spectrum was observed, but the tuning saturated when the reduction of persulfate became light limited. The tuning is attributed to the switching on of electroluminescence as electrons progressively populated particles of decreasing size, followed by switching off by Auger quenching when a second electron is captured before radiative decay occurs. (C) 1996 American Institute of Physics.