Optical properties of Pb doped TiO2 nanocrystalline thin films: A photoluminescence spectroscopic study

Pure and Pb doped TiO2 semiconductor thin films are deposited on single crystal Si (100) surface by a simple sol-gel method with a Pb content of 5, 10 and 15 mol%, under different temperatures (550, 750 and 850°C). The crystal structure, surface morphology and optical properties of the films, deposited on a Si (100) surface, have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy, respectively. XRD patterns indicate the amorphous/nanocrystalline nature of the films together with the presence of pure anatase (A) to an anatase/rutile (A/R) mixture as the temperature increases from 550°C to 850°C. The surface morphology of the films reveal a porous structure with particle size in the range of 15 nm to 100 nm. An intense green photoluminescence is observed in the visible region for pure TiO2 and the intensity gradually decreases by doping with lead, at all deposition (550, 750 and 850°C) and measuring (4.2, 77 and 300 K) temperatures.