光电材料及器件-光电材料.ppt

Low-dimensional nanostructural materials have attracted great interest because of their unique physical and chemical properties. Among these materials, ZnO, with a direct band gap of 3.37 eV and a large exciton binding energy of 60 meV, has been widely investigated, for potential applications in ultraviolet nanolaser sources, gas sensors, solar cells, and field emission display devices. In the past years, various approaches have been developed to synthesize ZnO nanostructures by means of hydrothermal, metal-organic chemical-vapor deposition, and physical vapor deposition. Recently, the application of ZnO in efficient solid state lighting is the subject of many studies. However, the light emission from ZnO is mainly based on optical pumping. Although a few electroluminescent devices based on ZnO have been reported, electroluminescent device of ZnO nanorods inorganic/organic hetero-structure is rare. Zinc oxide (ZnO), with its excellent luminescent properties and the ease of growth of its nanostructures, holds promise for the development of photonic devices. The recent advances in growth of ZnO nanorods are discussed. Results from both low temperature and high temperature growth approaches are presented. The techniques which are presented include metal–organic chemical vapour deposition (MOCVD), vapour phase epitaxy (VPE), pulse laser deposition (PLD), vapour–liquid–solid (VLS), aqueous chemical growth (ACG) and ?nally the electrodeposition technique as an example of a selective growth approach. Results from structural as well as optical properties of a variety of ZnO nanorods are shown and analysed using different techniques, including high resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), photoluminescence (PL) and cathodoluminescence (CL), for both room temperature and for low temperature performance. These results indicate that the grown ZnO nanorods possess reproducible and interesting optical properties. Results on obtaini