Controllable Adjustment Of Electrical Properties Of WO₃ Nanowires By H₂S Adsorption

Nanotechnology is the backbone of the modern science and technology. One-dimensional materials have established their place as candidates for next generation nano components because they present outstanding physical and chemical properties. WO3 nanowires gain extensive attention as an attractive material for electrochromism devices, gas sensors, memristors and superconductors. In this thesis, we report the observation of a new regime of operation where the memristor effect depends on various environments at room temperature. The main research results are as follows:1. Controllable preparation of quasi-one-dimensional WO3 nanostructures has been achieved through hydrothermal method, and mono-dispersed WO3 nanowires have been synthesized in large scale. The WO3 nanowires were characterized by SEM, XRD and EDS. The individual WO3 nanowire devices with the structure of metal/WO3 nanowire/metal have been fabricated by deep ultraviolet lithography and lift-off technology.2. Measurements are then carrying out in different environment(ambient and vacuum) at room temperature. Two ohmic contacts will be formed at the two contacts between the metal electrodes and the nanowire. Furthermore, the WO3 nanowires show a good memristor effects at the large voltage. Constant voltage scan with pulse were achieved to show the memristor effects more visually.3. Electrical transport properties characterization of the WO3 nanowires in air and hydrogen sulfide gas at room temperature. Experimental results indicate that H2 S adsorption will decrease the resistance of the devices and even reduce the memristor effects. At the same time, we did a control experiment at different relative humidity. Experimental results verified that H2 O adsorption will increase the resistance of the devices and even reduce the memristor effects.4. In this thesis, we find that WO3 nanowires memristor properties can be regulated by the test voltage. Measurements shows that I-V characteristics of WO3 nanowires can change from the intersection up of the "8" shape to the intersection down of the "8" shape.The results highlighted that this material can be applied in gas adsorption. At the same time, we hope that the memristor effect of WO3 nanowires can be controlled accuracy.