To verify theoretical model based on the surface depletion effect of oxide semiconductor in small crystallite, the SnO 2 particles of different crystallite size and donor density were prepared by controlling heat-treatment temperature and Fe 3+ doping concentration, respectively. In addition, Fe 3+-doped SnO 2 was compared with Fe 2O 3-loaded SnO 2 to discuss the effect of donor density. The electrical resistance and sensor response of prepared SnO 2 films were measured in various partial pressures of oxygen and hydrogen. As results, both undoped-and Fe 3+-doped SnO 2 showed the volume depletion in the oxygen concentration of more than 2.5% at 350°C. The dependence of electrical resistance on oxygen partial pressure for smaller crystallite had steeper slope. Furthermore Fe 3+-doping improved the sensor response to hydrogen, while the Fe 2O 3-loading did not work. Good agreement between experimental data the volume depletion theory was found.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Materials Chemistry
- Surfaces, Coatings and Films
- Renewable Energy, Sustainability and the Environment