Investigation On The Synthesis And Field Emission Properties Of ZnO Nanostructures

Zinc oxide (ZnO), as wide band gap semiconductor material, has good thermal and chemical stability, and its excellent luminescence, field emission properties have attracted much attention. Recently, there has been increasing interest in ZnO nanomaterials due to their unique properties.In this thesis, we briefly investigate the synthesis and crystal structure, photoluminescence and field emission properties of ZnO nanomaterials. It mainly contains the following works and innovations:1. The ZnO nanostructure with different aspects have been synthesized in many kinds of substrates (silicon, glass, copper,etc.) using thermal evaporation vapor phase transport and changing different technical parameters. The effects on sample aspect using different growth parameter have been compared, and the growth mechanisms have been analyzed, and the field emission properties have also been researched. The electron field emission properties show that the tetrapod-like nanowires has a low turn-on field at 2.9 V/μm, an emission current density of 1 mA/cm~2 is achieved at 5.4 V/μm owing to better high aspect ratio. For the nanorod sample, the field to obtain a current density of 1 mA/cm~2 is higher (at 6.2 V/μm) than that of the nanotetapod sample due to its bigger diameter, and its turn-on field is 3.3 V/μm. Both the ZnO nanotetrapods and nanorods have good field emission stability. Results indicate that both of the two nanomaterials are likely to be good field emission cathode.2. The patterned ZnO nanostructures grown on ITO-glass substrate have been researched. The patterned array with the unit area of～400×100μm~2 has been fabricated. The units are ordered and distributed uniformly, and the field emission performance is excellent, thus providing experimental foundation for realizing the all-glass encapsulation of field emission panel display.3. Two kinds of novel ZnO/ZnMgO heterostructures were fabricated, using a simple thermal evaporation method, through processes of low-rising-high temperature. They have single hexagonal wurtzite structure and they grow along c axis direction. The novel heterostructures and mechanism have been analyzed and discussed systematically. This preparation of microrods has good repeatability.