Porous silicon luminescence can be strongly modified by the applicatio
n of an external bias (energy-selective quenching of the photoluminesc
ence, reversible voltage tuning of the cathodic electroluminescence),
as the result of selective carrier injection into the silicon nanocrys
tallites of the porous layer. Partial oxidation of the material is sho
wn to strongly modify this selectivity and the voltage dependence of t
he light emission by changing the voltage drop distribution in the mat
erial.