A Metal-Insulator-Metal (MIM) diode is a device that can achieve rectification at high frequencies. The main objective of this research work is designing, fabricating, and characterizing thin film MIM diodes with single and multi-insulator layers. 
Cr/Al₂O₃/Cr and Pt/Al₂O₃/Al MIM diodes have been fabricated to show the impact of the materials on the current-voltage (I-V) curve. It is illustrated that the Cr/Al₂O₃/Cr MIM diode has a symmetrical I-V curve while the Pt/Al₂O₃/Al MIM diode has a very asymmetrical I-V curve. 
MIM diodes with single and multi-insulator layers have been fabricated to demonstrate the impact of the number of insulators on a MIM diode’s performance. It is found that by repeating two insulator layers with different electron affinities and keeping the total insulator thickness the same, the asymmetry and nonlinearity values show a significant improvement in a MIM diode. While the asymmetry of the diode with a double insulator layer (MI²M) is 3, it is 90 for the diode with a quadra insulator layer (MI⁴M), which 30 times greater than that of the MI²M diode.

Accurate assessment of the damage to buildings due to tunnelling in soft ground becomes an important issue when a tunnel is constructed under historic masonry buildings in urban areas. The current two-stage approach in which settlements estimated from a Gaussian curve are applied to a building does not consider soil-structure interaction and fails to give a correct prediction of the damage. This thesis describes a complete threedimensional finite element model for assessment of the settlement damage to masonry buildings induced by tunnelling in London Clay, and an investigation of the interaction between a masonry building and the ground. A macroscopic elastic no tension model, which assumes the material has zero tensile strength but infinite compressive strength, is developed to simulate the behaviour of masonry. Numerical techniques are proposed to improve the stability of the calculation. The comparison of the no tension and elastic models, by applying Gaussian curve settlement troughs to both a plain wall and a facade, shows that the no tension model predicts different behaviour of the masonry building during tunnelling, including different cracking patterns and damage grades. Two-dimensional finite element analyses combining the building, modelled by the no tension material, and the ground, modelled by a nested yield surface model, give insight into the interaction between the masonry structure and the ground. They suggest the importance of the stresses in the soil prior to the excavation in affecting the ground movements during tunnelling. Thus the weight of the building controls the overall magnitude of the ground movements beneath the building, while the stiffness of the building affects the shape of the trough. A key aspect of the behaviour of the masonry building is the formation of stress arches. Finally the three-dimensional finite element analyses are described. Both symmetric and unsymmetric cases are analysed. The results show that the three-dimensional analysis gives more realistic modelling of the problem and is likely to be necessary for practical situations, especially when a building is not symmetrically located with respect to the tunnel - a case which cannot be analysed in two-dimensions. A special tying scheme is proposed for the connection of the nodes belonging to elements of different types, which are defined in their own local co-ordinate systems. Different types of tie elements are formulated and implemented for connection between two-dimensional and three-dimensional elements in various combinations.

The fundamental atomic and electronic behaviour of clean silicon surfaces has been studied within a simple tight-binding picture of bonding in solids. Of the various contributions to the surface binding energy, the lowering in the promotion energy (i.e. rehybridization) which accompanies localized Jahn-Teller distortions has been identified as a major electronic driving force underlying the stability of silicon surfaces. The structure of Si(113) has been experimentally determined by the technique of scanning tunnelling microscopy (STM). Despite its high index, the Si(113) surface is found to be highly stable. STM images of both empty and filled states provide strong evidence for a particular structural model with a 3x2 unit cell. The STM results are explained in terms of a general rehybridization principle, suggested by the earlier theoretical study, which accounts for the low surface energy as well as the observed spatial distribution of empty and filled states. In addition, the STM images reveal a high density of domain boundaries which introduce energy states that pin the Fermi level and explain earlier reports of a 3x1 reconstruction for this surface. Voltage-dependent STM image simulations for the Si(113)3x2 surface have been carried out using a simple tight-binding description of surface electronic structure. Quantitative agreement with experiment is obtained confirming the qualitative rehybridization arguments used previously. The local barrier for tunnelling electrons is shown to have an important effect on the interpretation of STM images. The high stability of clean Si(l 13) is shown by STM to be disrupted by adsorption of submonolayer amounts of atomic hydrogen which saturates dangling bonds. Mass transport of silicon occurs and structural models are proposed for the resultant mixed 2x2 and 2x3 surface.

The Bolu Tunnels lie along Trans European Motorway (TEM) which is connecting Eastern Europe with the Middle East. The tunnels are approximately 3.0 km long, 40 m apart and have excavated cross sections more than 200 m2. In construction, New Austrian Tunneling Method (NATM) was used in soft ground. Due to the challenging ground conditions, many problems have been encountered during tunnelling. To solve these problems special construction techniques were adapted. To simulate and demonstrate the effectiveness of these construction techniques, 2D and 3D Finite Element Methods are utilized in this study. Through comparison between 2D and 3D modelling of advance of Bolu Tunnels, respective merits of these two approaches are investigated and the conditions under which shortcomings of the 2D approach become serious are identified.

This thesis demonstrates the effective use of low temperature molecular beam epitaxy to encapsulate planar Si:P (phosphorus-in-silicon) devices lithographically patterned by scanning tunnelling microscopy (STM) without significant redistribution of the dopants. To achieve this goal, low temperature magnetotransport is used in combination with STM, Auger electron spectroscopy and secondary ion-mass spectrometry to analyse Si:P ??-doped samples fabricated under different doping and growth conditions. An important aspect of this project is the use of large 1 ?? 1 cm2 Si(001) samples which are about five times larger than standard STM samples. The larger sample size is necessary for post-STM fabrication lithography processes in a cleanroom but presents problems for preparing atomically clean surfaces. The ability to prepare clean and atomically flat Si(001) surfaces for STM lithography on such 1 ?? 1 cm2 samples is demonstrated, and it is shown that Si:P ??-doped layers fabricated on these surfaces exhibit complete electrical activation. Two dopant sources (gaseous PH3 and solid GaP source) were investigated to assess their compatibility with STM-lithography on the H:Si(001) surface. The findings show that while the PH3 and GaP sources result in near identical electrical qualities, only PH3 molecules are compatible with H-resist based lithography for controlled nano-scale doping. For achieving complete activation of the P dopants, it is shown that an anneal to ??? 350 ???C to incorporate P atoms into the Si surface prior to encapsulation is critical. While it is known that the presence of H during growth degrades the quality of Si epitaxy, investigations in this thesis indicate that it has no significant effect on dopant activation. Systematic studies performed to assess the impact of growth temperature recommend an encapsulation temperature of 250 ???C for achieving optimal electrical qualities with minimal dopant segregation. In addition, it is shown that rapid thermal anneals (RTAs) at temperatures &lt 700 ???C provide only marginal improvement in the electrical quality of Si:P ??-doped samples encapsulated at 250 ???C, while RTA temperatures &gt 700 ???C should be avoided due to the high probability of dopant redistribution. To elucidate the nature of 2D transport in Si:P ??-doped devices, a detailed analysis of the low temperature magnetotransport for Si:P ??-doped layers with doping densities in the range ??? 0.2 ??? 2 ?? 1014 cm???2 was carried out. Using conventional 2D theories for disordered systems, both weak localisation (WL) and electron-electron interactions (EEI) are shown to contribute almost equal corrections to the 2D conductivity. In particular, it is found that EEI can introduce a significant correction in the Hall coefficient RH (hence Hall density) especially in the low density/temperature regime and the need to correct for this when using the Hall density to estimate the activated electron density is highlighted. While the electronic mean free path in such highly doped ??-layers is typically &lt 10 nm making ballistic transport in these devices difficult to observe, the phase coherence length can extend to almost 200 nm at about 0.3???0.5 K for doping densities of ??? 1 ??? 2 ?? 1014 cm???2. Finally, the optimised encapsulation strategy developed in this thesis is applied to a 2D square device fabricated by STM. The device exhibits Ohmic conductivity with complete dopant activation. An analysis of its low temperature magnetotransport shows that the device behaves similarly to a Si:P ??-doped layer encapsulated under similar conditions, thus highlighting that the STM patterning process had no adverse effect on device quality.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [95]-100).

Thesis (Ph.D)--Physics, Georgia Institute of Technology, 2008. / Committee Chair: Dragomir Davidovic; Committee Member: Alexei Marchenkov; Committee Member: David Citrin; Committee Member: Elisa Riedo; Committee Member: Walter A. de Heer. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.S.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 57-59).

Thesis (Ph. D.)--University of Alberta, 2009. / Title from PDF file main screen (viewed on Oct. 19, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy, Department of Physics, University of Alberta." Includes bibliographical references.

Thesis (Ph. D.)--University of Chicago, Dept. of Physics, December 2000. / Includes bibliographical references. Also available on the Internet.