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Abstract:

Besides being used in industries to produce protective or decorative coatings, electrodeposition has become a well established method for fabrication of semiconductors, solar cells and materials used in computer chips and magnetic data storage system. However, the application of this simple, low cost, and scalable method for light emitting diodes (LEDs) has not been fully explored. ZnO based LEDs have attract a lot of attention recently. The direct wide band gap semiconductor ZnO has large exciton binding energy (60 meV) and its wurtzite crystal structure matches closely that of conventional LED semiconductor of GaN. In addition, ZnO is chemically stable, non-toxic, low cost, and relatively abundant. As a result, LEDs consisting of ZnO p-n homojunction and heterojunction of n-ZnO with various p-type semiconductors have been intensively investigated. In this talk, the progress of fabricating ZnO based LEDs using cost-effective and low-temperature electrodeposition method will be presented. The morphologies of ZnO films and ZnO nanorod arrays together with their optoelectronic properties are closely related to electrodeposition conditions, such as precursors, solution concentrations, additives, solvents, substrates, deposition voltages and currents. We have successfully fabricated prototype LED devices with different light emitting colors for several device architectures, such as GaN/ZnO, CrO₃/ZnO, NiO/ZnO LEDs. This technique is applicable to both commercial p-type semiconductor wafers, such as GaN, as well as making all semiconductor layers by electrodeposition on ITO/FTO glass.

Coffee and tea will be served 20 minutes prior to the seminar.