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Title: Pulsed laser synthesis of nanostructures for large area nanoelectronics
Author: Jayawardena, Koruwakankanange Don Gershon Imalka
ISNI:       0000 0004 2717 2582
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 2012
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The work discussed in this thesis focuses on synthesis of amorphous carbon and zinc oxide nanostructured for application as electrodes and for gas sensing. The synthesis of nanostructured carbon has been achieved through the ablation of either a pyrolytic graphite target or a pressed carbon/nickel composite target into an Ar atmosphere which is observed to modulate the morphology of the nanostructures. Furthermore, the ablation of the composite target is observed to lead to a non-congruent material transfer with increased Ni content in the deposited nanostructure. The incorporation of Ni combined with graphitisation due to thermal annealing is observed to improve the electrical characteristics of the alloyed nanostructures in comparison to the pure carbon nanostructures. The application of smooth films (both pure and alloyed) as electrodes for diamond-based radiation detectors is discussed. Furthermore, the performance of thermally annealed highly cluster assembled carbon films for NH3, NO2 and humidity sensing is also discussed. The use of excimer lasers in order to affect the reaction rate and control of size and shape distribution of ZnO nanocrystals grown in liquid phase has been studied in relation to the laser fluence and processing duration for a fixed repetition rate and bath temperature. A growth window for laser fluence is observed where morphology controlled nanocrystals can be prepared through a photothermal breakdown process. The use of size (distribution) controlled nanocrystals for thin film transistors is discussed. In addition to its application as a material for transistors, the use of thin film nanocrystals for humidity and NO2 sensing is also discussed. While high performance is observed for humidity sensing, the films do not show a repeatable performance upon exposure to NO2, which is attributed to the poor desorption of the adsorbed analyte. Finally, the use of the above nanocrystals as a seed particle for hydrothermal growth of ZnO multipods is discussed together with its use for UV and vapour sensing.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available