Preparation, Magnetism And Optical Properties Of ZnO Nanostructures Doped By 3d Transition Metal

As a typical II-VI wide band semiconductor material, ZnO has been a hot topic in the material research due to its multiple of morphology and properties. Compared with Si and GaN, ZnO has a wide band (3.37eV) and high exciton banding energy (60meV), and it not only has good electronic and optical properties, but also can form diluted magnetic semiconductor by transition metal doping. So, ZnO is expected to become the next generation material in information processing and storage, quantum computing and quantum communication, and it has a broad application prospect in short wavelength laser and spintronic devices.In this paper, hydrothermal method is used to make intrinsic ZnO material. The zinc acetate is used as row material, sodium hydroxide as mineralizer. By simply changing reaction conditions, such as:zinc salinity,mineralizer type,temperature,reaction time and so on, different kinds of ZnO nano materials can be synthesized, which include nanopieces,nanorods,nanowires and nanoflowers. What's more, growth rhythms and the relations between features and photoluminescent properties are studies as well. The test result suggests: [OH-] concentration is the element which influences the axis growth of ZnO nanowires. Single ZnO nanowire grows longer while [OH-] concentration increases. Also, reaction temperatures are the elements which influence radial direction growth and nucleation rate. ZnO nanowires grow as the reaction temperatures increase. Reaction time is the element that influences radial direction growth rate, which shows extent of reaction. Different ZnO structures show different photoluminescence properties. Nanopieces have the strong purple emission spectrum, while the nanorods show strong green emission spectrum. These are all due to the different defection type.Based on the process of ZnO nanorods,3d transition metals Co,Mn,Ni have been introduced to prepare well photoluminescence and room-temperature ferromagnetism materials. Research tests show that:ZnO doped by 1% Co show room-temperature ferromagnetism, which also have strong purple emission spectrum. ZnO doped by 1% Mn show diamagnetism properties, while doped by 2% Mn, ZnO show room-temperature ferromagnetism, which also have the strong ultraviolet spectrum.at 390nm. Also, ZnO doped by 0.5% Ni, show oom-temperature ferromagnetism, which has effects on purple emission spectrum. Doping can help to change the defect concentrations, which have the effect on photoluminescence properties. The reason of ferromagnetism at room temperature is the spinning exchange among carriers.