The existence of an outer cracked layer and an inner more structured p
orous layer has been observed in electrochemically obtained porous sil
icon when drying procedures ale carried out, The changes in the charge
transferred to the porous structure during voltammetric oxidation, th
e interference fringes obtained by Fourier-transform infrared spectros
copic measurements, and scanning electron microscopy micrographs confi
rm the existence of this double layer Also, drying procedures and volt
ammetric oxidations drastically affect the intensity and wavelength of
the peak maximum in the pbotoluminescence spectrum. The evolution of
the luminescent properties is explained by the introduction of nonradi
ative recombination centers. (C) 1996 American Institute of Physics.