Hot carriers and excitation of Si/SiO_x interface defect photoluminescence in Si nanocrystallites

In low-dimensional silicon wires and dots, as supposed earlier (Phys. Rev. B 65 (2002) 115313), hot carrier ballistic transport towards the Si/SiO _x interface can enhance the excitation of oxide defect-related photoluminescence (PL) bands. This article presents new experimental results supporting the role of ballistic transport in bright visible photoluminescence of silicon nano-crystallites. The intensity dependences of the "red" and "orange" photoluminescence bands on excitation light wavelengths, diameters of Si nano-crystallites and surface area of porous layers have been analysed. The models of optical transitions at the excitation of both PL bands are discussed as well.