Research On Gas Sensing Properties Of TeO₂ Quasi-one-dimensional Nanostructures

TeO2 is a p-type semiconductor material, which has a wide band gap. It is highly sensitive to redox gas and shows superior performance in the aspect of gas sensitive sensor. In this thesis dissertation, we delve into the gas-sensitive properties of TeO2 nanowires at room temperature.TeO2 nanowires were synthesized on Au-coated Si substrate by chemical vapor deposition using Te powder as the source material. The gas sensor was prepared by using TeO2 nanowires as the sensing material.Microstructure characterization by means of XRD and SEM shows that TeO2 nanowires are single phase of tetragonal structure. The nanowires were approximately several tens of micrometers in length and 50~200nm in diameter. There are no Au particles on the tip of TeO2 nanowires,revealing that TeO2 nanowires grow according to the vapor-solid mechanism.Resistive sensors based on individual TeO2 nanowires with the structure of metal/TeO2 nanowire/metal have been fabricated by wire mask. Electrical transport properties of these devices have been tested at room temperature in air, vacuum and hydrogen sulfide gas. In the atmosphere, the density of hole concentration increases due to the oxygen adsorption resulting in the increase of electrical conductance while theconductance of the device is reduced in the strong reducing hydrogen sulfide gas. The memristive mechanism is found in the course of testing.In our experiment, the memristive effect is enhanced by air while restrained by H2 S, which explore the memristive mechanism: the removal of oxygen vacancy change the barrier width, which give rise to the change of electric conductance.It is showed that quasi-one-dimensional tellurium dioxide nanowires are highly sensitive to redox gas at room temperature. So it is possible to realize the high-performance gas sensor of low power consumption working at room temperature.