Thesis (M.Med.Sc.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 89-98).

published_or_final_version / Anatomy / Master / Master of Medical Sciences

Miniaturization of electronics is an unstoppable trend in the semiconductor industry. Moore’s Law has been the driving force to the advancement of the industry for half a century; and will continue to be the indicator for technology developments. As the feature size of an electronic device is reducing to the nano-scale level, quantum mechanics and atomistic details will become more and more important. In addition, simulations on devices with two or more terminals, such as transistors or junctions, are essential for design of electronics. Thus, Quantum mechanics based method with atomistic details for simulations of nano-electronic devices with two or more terminals is proposed and demonstrated. Similar studies can be found in the literature. However, most work was focusing on static / steady state problems, only few had looked into the dynamics. On the other hand, most methods being used in previous work can only handle two-terminal devices, while those few methods which can be applied for multi-terminal devices can only deal with steady state problems. Therefore, there is a research gap lies in multi-terminal time-dependent device simulations; and this gap will be filled by the work in this thesis. Quantum mechanics based method for open system has been used to simulate the electrical response through nano-electronic devices. Nearest neighbor tight binding models and carbon based models are the systems of interests. The core part of the structures of the systems of interest is a hexagonal ring. This is essentially a benzene ring based structure in our studies. Several situations for electrodes connecting the benzene ring at para- and metapositions are considered. Two-terminal cases and three-terminal cases for the mentioned systems have been studied. The third terminal in the three-terminal case is basically being viewed as a probe to the corresponding two-terminal case. For all the cases, steady state currents have been calculated; and currentvoltage curves of the systems have been obtained. Transient currents have also been calculated, so that dynamic responses of the systems are revealed. Different magnitudes of bias voltages have been applied to the systems. Linear response of the currents through the devices with respect to the bias voltage is observed for most cases. The para-position case can be taken as a reference to the meta-position case, due to simple structure and well-behaved responses. Interesting electric responses from the meta-position case is observed. The possibility for the meta-position system to be used as a transistor or other devices is briefly discussed. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

As the fast development of nanotechnology and further industrial applications, theoretical investigations upon nanoscale devices are in urgent need. Until now several formalisms have been well established in quantum transport of mesoscopic areas, including of tight-binding and first principle calculations. In this dissertation those methods were partly explored to explore transport and thermoelectric features in various models and actual devices. The density functional theory plus non-equilibrium Green’s function serves well in the probing process of transport properties like conductance in mesoscopic systems. Atoms’ positions were treated as the only input parameters and one computation package based on NEGF-DFT loop was utilized to get the numerical results, then the corresponding thermal quantities were analysed. The coherent transport exhibits an obvious character in transmission spectrum called transmission node, whose existence relies on the asymmetric structure of molecular junctions. In the main body of the thesis, firstly two types of model simulation were tested, and the following thermoelectric quantities showed that there’s one interesting signature in the thermopower performance, which was its temperature independence around transmission node. Through comparisons between different system parameters a rough regular pattern was obtained, that the degree of zero transmission and the energy difference around it influenced this temperature invariance feature at the same time. While these two properties were mainly determined by the natural structure of devices. Besides model simulations the ab initio investigations were also carried out. Although the actual device was not easily altered as ideal models, some similar behaviours in the transmission and thermal curves were still found out. The temperature insensitivity was considered to appear more often in a π electron dominated molecular structure rather than ones with σ electron interactions. / published_or_final_version / Physics / Master / Master of Philosophy

No description available.

DNA is a remarkable material that is both an inspiration for polymer nanotechnology and a versatile building block for assembling well-defined nanostructures. To create polymeric materials that would be useful in nanotechnology, we synthesized block copolymers containing thymine and diamidopyridine side chains. These DNA-mimetic polymers self-assembled into spherical aggregates in solution, held together by hydrogen bonding interactions. We have reported the first example of a block copolymer micellar aggregate that is capable of selective recognition of small-molecule guests, with concomitant changes in its aggregation behavior. / In the field of DNA-mediated materials, the ordering of gold nanoparticle (AuNP) arrays can be hindered by the lability of AuNP-DNA linkages. In the search of an indefinitely stable AuNP-DNA linkage, three dendritic thiol-terminated DNA strands were synthesized, and were bound to AuNPs. A preliminary AuNP-DNA linkage lability study showed potential in forming nonlabile AuNP-DNA linkages through the use of dendritic thiol-modified DNA.

Thesis (M. Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on July 13, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Masters [sic] of Science in Micro-Electro-Mechanical-Systems (MEMS) and Nanosystems, Department of Electrical and Computer Engineernig [sic], University of Alberta." Includes bibliographical references.

No description available.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Whetten, Robert; Committee Member: Bottomley, Lawrence; Committee Member: de Heer, Walter; Committee Member: El-Sayed, Mostafa; Committee Member: Fernandez, Facundo; Committee Member: Gordon, Sidney; Committee Member: Leavitt, Andrew; Committee Member: Orlando, Thomas. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph.D)--Chemistry and Biochemistry, Georgia Institute of Technology, 2010. / Committee Chair: Lawrence A. Bottomley; Committee Member: Aldo A. Ferri; Committee Member: Andrew Lyon; Committee Member: Jean-Luc Bredas; Committee Member: Robert L. Whetten. Part of the SMARTech Electronic Thesis and Dissertation Collection.