The effect of Ti on physical properties of Fe2O3 thin films for gas sensor applications

Hematite (Fe2O3) and titanium (1 wt% and 3 wt%) doped Fe2O3 were prepared onto glass and p-type silicon wafer using the pulsed laser deposition technique. X-ray diffraction analysis indicates that samples of pure and Ti-doped were polycrystalline with a crystal orientation along (113) plane. The average grain size increases with the increasing titanium content. Surface morphology was studied through a Scanning Electron Microscope (SEM) and Atomic Force Microscopy (AFM), which reveal that grains are columnar in shape. UV-visible transmission spectroscopy reveals that the deposited films are transparent within a visible range. The value of the optical bandgap exhibits a decrease from 1.93 eV to 1.48 eV as titanium concentration increases. Gas sensitivity measurements at 30°C. showed a decrease in sensitivity with the increase of doping and gas concentration.