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.