Gas-sensing features of nanostructured tellurium thin films

Abstract

<jats:p>Nanocrystalline and amorphous nanostructured tellurium (Te) thin films were grown and their gas-sensing properties were investigated at different operating temperatures with respect to scanning electron microscopy and X-ray diffraction analyses. It was shown that both types of films interacted with nitrogen dioxide, which resulted in a decrease of electrical conductivity. The gas sensitivity, as well as the response and recovery times, differed between these two nanostructured films. It is worth mentioning that these properties also depend on the operating temperature and the applied gas concentration on the films. An increase in the operating temperature decreased not only the response and recovery times but also the gas sensitivity of the nanocrystalline films. This shortcoming could be solved by using the amorphous nanostructured Te films which, even at 22 °C, exhibited higher gas sensitivity and shorter response and recovery times by more than one order of magnitude in comparison to the nanocrystalline Te films. These results were interpreted in terms of an increase in disorder (amorphization), leading to an increase in the surface chemical activity of chalcogenides, as well as an increase in the active surface area due to substrate porosity.</jats:p>

GAS SENSITIVE FILMS BASED ON Te-SnO2 NANOCOMPOSITE ON FLEXIBLE SUBSTRATE

“…The main methods of the fabrication of gas sensitive Te based films implies the thermal vacuum evaporation of either pure polycrystalline Te or its alloys, pulsed laser deposition [31], the rf sputtering [32] or direct vapor phase process [33] in an argon atmosphere. The films usually were grown onto hard substrates of glass Pyrex, quartz, sintered or porous alumina [34], Si / SiO 2 wafers and others.…”