Photoluminescence studies of ZnO/porous silicon nanocomposites

This paper reports on the intense broadband photoluminescence (PL) emission from the ZnO/porous silicon nanocomposite films. The porous silicon (PS) samples were formed by electrochemical anodization on p-type (1 0 0) silicon wafer and ZnO thin films are deposited by the sol–gel spin coating technique in the pores of PS. The average pore size of PS samples is 30 nm. The glancing angle x-ray diffraction pattern of as-deposited and annealed films shows that the quality of (0 0 2) oriented ZnO nanocrystallites improves with annealing at moderate temperature and are polycrystalline in nature. The average crystallize size was found to be 40 nm. The surface topography of the ZnO/PS nanocomposite films has been studied using atomic force microscopy. The mechanism and interpretation of broadband PL from 400 to 900 nm of the nanocomposites are discussed using oxygen-bonding and native defects models for PS and ZnO, respectively. These nanocomposite films could be used as a source of broadband luminescence across most of the visible spectrum.