Pulsed laser deposition of WO3-base film for NO2 gas sensor application

Pulsed laser deposition (PLD) technique was used to deposit Al- and Ti-doped WO3 films. Only under certain circumstances, did the stoichiometry of the targets compile with the films. The as-deposited films of the doped WO3 were half-crystallized triclinic WO3. After being annealed at 500°C for 2 hours, tetragonal structure of WO2.90 was formed. Due to the much smaller crystallites in the films of WO2.90, the Al and Ti dopant greatly improved the sensitivity of the films to NO2.