Ballistic effect and photoluminescence excitation in porous silicon

This article presents experimental results supporting the role of the ballistic transport in strong “red” photoluminescence (PL) of porous silicon (PSi). It is shown that this PL band connects with emission of oxide-related defects at the Si/SiOx interface. The dependence of an intensity of interface-defect related photoluminescence on morphology and the average size of Si nano-crystallites on porous silicon surface has been investigated. The peculiarities of Raman and PL excitation spectra in dependence on the average size of Si nano-crystallites have been studied as well. Confirmation of ballistic effect role is important for understanding the photoluminescence mechanism in Si nano-crystallites and successful application of silicon low-dimensional structures in optoelectronics.