The growth and characterisation of ordered arrays of zinc oxide nanostructures and optical studies of defects in zinc oxide
Byrne, Daragh (2012) The growth and characterisation of ordered arrays of zinc oxide nanostructures and optical studies of defects in zinc oxide. PhD thesis, Dublin City University.
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In this work the growth of c-axis aligned zinc oxide nanorods on non-epitaxially matched substrates is examined. Nanorod arrays were deposited on silicon by seeding and chemical bath deposition (CBD), carbothermal vapour phase transport (CTR-VPT) and a hybrid CBD / CTR-VPT method. The best optical quality nanorods were obtained by the hybrid CBD / CTR-VPT method. This hybrid method was extended further and a method was developed to deposit hexagonally close packed positioned c-axis aligned arrays using a facile nanosphere technique in conjunction with silica templating. The varying factors affecting the deposition process were examined, including the growth conditions, transformations in the CBD layer during high temperature CTR-VPT deposition and the formation of new interfaces between the substrates and nanorods. The optical properties of the nanorod arrays were examined by low temperature Fourier transform photoluminescence spectroscopy, where it was found that the quality of both the positioned and unpositioned nanorods was excellent. Work on an important deep level emission in ZnO (the structured green band) was also undertaken, both in nanostructures by deliberately introducing copper into the growth process and also by a soft Cu isotopically specific doping technique into highly perfect single crystals. These samples’ properties were then studied by low temperature photoluminescence spectroscopy.
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