Preparation And Sensitive Properties Of WO₃Nanostructures

Nanotechnology is promoting the progress of technology as well as improving the degree of social civilization and the quality of life with its unique properties, since it was born in the1980s. Nowadays numerous scientists all over the world are devoting themselves to the study of nanotechnology and trying to achieve rapid development in it.Tungsten trioxide (WO3) is a kind of N-type semiconductor with an energy gap of2.6eV, belonging to the transition metal oxides. The surface volume ratio of low-dimensional WO3nano-materials is high, which performs the photoelectric effect with the generation and combination of electron-hole pairs under the light. With the unique physics and chemistry properties, WO3is applied in many fields such as gas sensor, photocatalyst and electrochromic device, etc. With the trend of optoelectronic devices miniaturization, the nanostructure is becoming the basic materials of optoelectronic devices. And it is significant to do some research about the electrical transport properties and gas sensitive properties of nanostructure before it is applied to the electron device.The research about the nanostructure of WO3in this paper includes five sections as follows:(1) Use the method of chemical vapor deposition (CVD) to complete the synthesis of WO3nanowires and try to find an economic, convenient, effective and repeatable growth method. Then adjust the key conditions which affect the final results such as the atmosphere and temperature. Try to find how these key conditions affect the results and prepare the high quality nanowires.(2) Deposit the ZrO2and WO3film with the interdigital electrode substrate by sputtering method. Take control of sputtering time and sputter ZrO2as the first layer of material on the electrode for10min,20min,30min, and40min. And then sputter WO3for100min on four electrodes. All the electrodes showed tunnel effect in the test and with the increasing thickness, the possibility of tunneling effect was decreasing.(3) Analysis the nanowires and nano film. Use the transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and energy disperse spectroscopy (EDS) to analysis the morphology, composition and structure of nano-materials and determine the microstructure of nano-materials.(4) Prepare the photoelectric detector with WO3nanowires to test the basic properties of WO3nanowires. Test its photoelectric response under UV LED and its gas sensitive response in the oxidizing gas such as O2and NO2. (5) Put the interdigital electrodes with WO3film under UV LED to test the photoconductive properties. The electrodes appeared a phenomenon of persistent photoconductivity (PPC). In order to explore the influencing factors of PPC phenomenon, put the electrode in different atmosphere. And PPC phenomenon does not relieve. But PPC phenomenon relieves after the electrode having an annealing process. It shows that annealing is helpful to reduce crystal defect and improve the performance of crystal.