Structural and luminescence studies on TiO2-MoO3 thin films

Thin films of MoO 3 and TiO 2 -MoO 3 were deposited on quartz glass and Silicon (100) substrates by dc magnetron sputtering at two substrate temperatures of 300 K and 600 K and at two sputtering pressure of 5 Pa and 10 Pa and sputtering power of 50 W respectively. The deposited films were characterized by X-ray Photo Electron Spectroscopy (XPS), Raman and photoluminescence spectra. The pure MoO 3 films deposited at 300 K exhibited the Raman bands at 242 cm −1 and 974 cm −1 indicating the absorption of water molecules and formation of alpha MoO 3 -H 2 O. With increasing Ti content the bands are shifted to 224 cm −1 and 960 cm −1 that correspond to h-MoO 3 and absorption of water molecules. For Ti at. % of 2.4 the bands were observed only at low frequencies but at high temperatures, a single peak noticed at 954 cm −1 corresponds to α – MoO 3 H 2 O. The Photo-luminescence spectrum reveals that the MoO 3 films deposited at 5 Pa and 300 K exhibits Near Band Edge (NBE) transition at 324 nm. The intensity of NBE increases further and with corresponding shift towards higher wavelength with TiO 2 doping. The TiO 2 doping also introduces Deep Level (DL) emission in TiO 2 -MoO 3 composite film. With increase of deposition temperature the intensity of emission due to NBE in MoO 3 films decrease introducing DL emission. The TiO 2 doping enhances the intensity of both NBE and DL emission with a shift in emission wavelength towards higher value. The intensity of these NBE and DL emissions are further increasing with increasing sputtering pressure (10 Pa) and deposition temperature (600 K) of MoO 3 and TiO 2 -MoO 3 . Graphical abstract The MoO 3 and TiO 2 -MoO 3 thin films were deposited by d.c. magnetron sputtering at different temperatures and sputtering pressures. From XPS, it is observed that there is a shift in binding energy position of Mo characteristic peak towards higher energy due to Titanium doping, when compared to Mo binding energy peak in case of MoO 3 films. The Raman spectra results indicates that the TiO 2 affecting the crystallization of MoO 3 films and crystallizing them from orthorhombic to monoclinic phase with increasing Ti atomic percent The Photoluminescence spectra reveals that a high intense light emission from TiO 2 - MoO 3 thin films deposited at 10 Pa and 600 K.