Fabrication And Optoelectronic Properties Of Oxide Semiconductor Nanostructures

Oxide semiconductor nano-materials have demonstrated a very good prospect, and more in-depth work involves the application of nano-materials and building on nano-devices. Current study focused on the performance of the prototype device. In this paper, we focus on testing and evaluation the performance of the nano-structured materials and nano-device. Oxide semiconductor nano-materials have demonstrated a very good prospect, and more in-depth work involves the application of nano-materials and building on nano-devices. Current study focused on the performance of the prototype device. In this paper, we focus on testing and evaluation the performance of the nano-structured materials and nano-device.For the composite oxide semiconductor nano-thin films, understanding the excellent physical properties of the composite system should be solved. We chose the energy level matching system of WO3/TiO2 composite films for studying. And we investigated the electron transport property at the interface of complex thin film in nano-scale scope in order to provide experimental support for the theoretical basis. With the future application for fabricating nano-devices, quasi-one-dimensional nano-structure will played a significant role. In the process of building devices, the contacts between the metal electrodes and the semiconductor, as well as their transport properties of semiconductor are still have many problems. Especially for oxide semiconductor nano-materials, the oxygen vacancies can form surface states to influence the device performance. In addition the light can stimulate the semiconductor oxides which control the transport property of the device.In the chapter 1, we reviewed the property of the oxide semiconductor nanomaterials and the measurement methods of nano-structures. We find out the problems in current stage. Therefore we get the research objectives and the main research contents in our future works.In the chapter 2, we prepared nano-composite structure of WO3/TiO2 films. Using a more direct characterization of the performance of charge-transfer model of KFM, the charge-transfer process is studied. The results showed that, due to tungsten trioxide and titanium dioxide energy levels matching relationship, the charge transfer does occur. Multi-layer composite structure WO3-TiO2 nanometer thin films are also investigated and the multi-layer composite of WO3-TiO2 have optical switching effect for both positive and negative directions. All these studies would be very good theoretical works for the development of a new type of thin-film nano-optoelectronic devices.In the chapter 3, hexagonal tungsten trioxide (WO3) nanowires were prepared on Si substrate by thermal evaporation of tungsten trioxide powder. As-prepared single WO3 nanowire was assembled across the opposing Pt electrodes. Theâ… -â…¤characteristics of WO3 nanowire with and without UV illumination had been investigated. The results showed marked rectifying behavior was obtained in dark condition. Under UV illumination, theâ… -â…¤characteristic of WO3 nanowire could be greatly changed which showed that the nano-metal/semiconductors (nano-M/SCs) might have potential applications in optoelectronic nano-devices.In the chapter 4, a single SnO2 NB is aligned across opposing Au electrodes by dielectrophoresis technique. We investigate theâ… -â…¤characteristics of a single SnO2 NB with and without UV illumination on Au electrodes and theâ… -â…¤characteristics exhibit nonlinear and asymmetric behavior under dark condition. The nonlinear electrical transport behavior indicates that the back-to-back Schottky barriers structure is formed. The origin of the asymmetricâ… -â…¤curve and the response for UV illumination of the nano-M/SCs are investigated also. The transport property of SnO2 NB and the contact properties between SnO2 NB and the electrodes will be of great importance for fabrication of SnO2 nanodevices in the future. According to different time periods of theâ… -â…¤curve testing analysis, we found in 2 minutes the light can reach the maximum photocurrent. In tin dioxide nano-devices, we found storage and electrical switching effect with voltage scan. This phenomenon has not yet been reported based on the tin oxide nanobelts nano-devices. The reason of resistance switching effect is that the Schottky contact between the nanobelt and the metal electrodes, while the bias voltage can cause oxygen desorption and change the Schottky barrier height, which played a role in the switch effect. Tin oxide nanobelts show a series of excellent properties, the current maps of the nanobelt were also studied by C-AFM, the Schottky diode behavior would be visualized in our current maps by C-AFM technique, which correlating the microscopy with separate transport properties measurement together.In Chapter 5, SnO2 nanobelts were synthesized by thermal evaporation of SnO2 powder. As-prepared SnO2 nanobelts were immerged into the Ag colloids and then the Ag/SnO2 nanobelts were obtained. We also characterized the Surface photovoltage (SPV) of SnO2 nanobelts and Ag/SnO2 nanobelts. The results show that the SPV signal of Ag/SnO2 nanobelts was attributed to the formation of the Schottky junction between the Ag nanoparticles and SnO2 nanobelts. Conductive atomic force microscopy was used to study the micro current distribution of the composite structure Ag/SnO2 nanobelts. Ag/SnO2 nanobelt is aligned across opposing Au electrodes by dielectrophoresis techniques, the results show that the current was decreased by loading of Ag nanoparticles which is due to the Schottky junction in the local area between the Ag particles and the SnO2 nanobelts. We also prepared composite nano-structures of ZnO /SnO2 by vapor deposition method and morphology of composite structures were analyzed.In the chapter 6, we made a conclusion of the researches of this paper, and expected the future investigations on the oxide semiconductor nano-materials.