Nanostructures of magnesium (Mg) doped Zinc oxide (ZnO) were successfully deposited on conducting fluorine-doped tin oxide (FTO) coated glass plates by cathodic electrochemical deposition method at different potentials and temperature conditions. The deposited samples were characterized by XRD and SEM techniques to confirm their structures, morphologies and optical properties. These measurements show that Mg doped ZnO has a wurtzite structure and that the strongest intensity of the (002) peak is found at 60 degrees C and -1.0 V. Tunable transmittance of Mg doped ZnO has a band gap energy from 3.45 eV to 3.82 eV, which is the direct evidence of doping.

Tin dioxide nanotubes (200 nm in diameter) were synthesised by the sol-gel template method. The gas sensitivity of SnO2 nanotubes has been investigated. Due to the small grain size and large amount of grain boundary, SnO2 nanotubes demonstrated good sensitivity in sensing ethanol gas and had an ability to detect ammonia gas without any doping or surface modification. In2O3 semiconductor nanowires were synthesized efficiently by the chemical vapor deposition method through carbon thermal reduction. The diameter, length and morphologies of In2O3 nanowires can be varied by controlling the synthetic conditions. The In2O3 nanowires were characterised by field emission scanning electron microscopy (FE-SEM) and high resolution transmission electron microscopy (HRTEM). The application of In2O3 nanowires for gas sensors was tested.