Photoluminescence (PL) and photoluminescence excitation (PLE) studies
are carried out on porous silicon (PS) layers anodically oxidized in N
H4NO3-ethylenglycol electrolyte. PLE spectra reveal monocrystalline si
licon like features after removing the oxide shelf of crystallites by
chemical etching. Its reconstruction during oxidation in air atmospher
e seems to increase mechanical stresses in silicon nanocrystallites. A
s a result, the PLE spectra, absorption and emission properties of PS
are changed considerably.