PHOTOLUMINESCENCE OF ANODICALLY OXIDIZED POROUS SILICON

A photoluminescence (PL) study is carried out on porous silicon (PS) l ayers of 50 to 60% porosity which are anodically oxidized in ethylengl ycol-NH4NO3 electrolyte. Such oxidation is found to make the PL intens ity stronger and the peak wavelength shorter. The emission of partiall y linearly polarized light is observed for PS samples under linearly p olarized light excitation. Transmission IR and reflectance spectra are recorded to characterize porous silicon. As a result, a strong shift of the absorption band edge and high silicon oxide content are found i n PS samples. This shift is supposed to be due to the quantum confinem ent mechanism, but the features of PL speak in favour of the important role of oxide in the light emission from PS. In particular, the polar ization of the emitted light can be due to the oxide-induced elastic s trains.