| AVS 56th International Symposium & Exhibition | |
| Thin Film | Tuesday Sessions |
| Session TF1+SE-TuM |
| Session: | Glancing Angle Deposition I |
| Presenter: | D. Deniz, University of Maine |
| Authors: | D. Deniz, University of Maine R.J. Lad, University of Maine |
| Correspondent: | Click to Email |
The sensitivity of chemiresistive metal oxide gas sensors can be markedly increased by fabricating nanostructured films with very high surface to volume ratio. In this work, nanostructured tungsten (W) and tungsten oxide (WO3) films were fabricated using pulsed direct current (DC) magnetron sputtering of a W target with a glancing angle deposition (GLAD) geometry. The major parameters that were varied included substrate temperature, deposition rate, substrate rotation, Ar/O2 plasma composition, and post-deposition thermal treatments. The stoichiometry of the nanostructured films was characterized by X-ray photoelectron spectroscopy (XPS), and the structure and morphology were investigated using X-ray diffraction (XRD) and high resolution scanning electron microscopy (SEM). Metallic W nanorods were formed by sputtering in a pure Ar plasma at room temperature and they crystallized in a simple cubic β-phase with W(100) texture. Subsequent annealing at 500 °C in air transformed the nanorods to textured triclinic WO3 structure but the nanorod morphology was retained. Stoichiometric WO3 films grown in Ar/ O2 plasma at room temperature had an amorphous structure and also exhibited a nanorod morphology. Post-deposition annealing at 500 °C in air induced crystallization to the triclinic WO3 phase and also caused a morphological change into a very nanoporous network. The differences in the chemiresistive response to each of these high surface area nanoengineered films to CO2 and CH4 gas exposure will be presented.