QUANTUM CONFINEMENT EFFECT IN ELECTROLUMINESCENT POROUS SILICON

The voltage-tuned electroluminescence (EL) of n-type porous silicon (P S) in a persulphate solution under cathodic polarization was studied. A blue shift with the increase oi cathodic polarization and a time-dep endent red shift at constant potential of EL spectra have been observe d. To investigate the voltage tuning mechanism and luminescence quench ing mechanism for the electroluminescence of PS, FT-IR, AFM and electr ochemical methods were used. The results show that the voltage-tuned e lectroluminescence can be attributed to the selective excitation of di fferent sizes of PS crystallites, which agrees with the ''quantum conf inement model'' in PS luminescence.