published_or_final_version / Physics / Doctoral / Doctor of Philosophy

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

published_or_final_version / Electrical Engineering / Master / Master of Science in Engineering

published_or_final_version / Physics / Master / Master of Philosophy

published_or_final_version / abstract / Physics / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Physics / Doctoral / Doctor of Philosophy

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

Efforts to increase productivity, reduce time to market, reduce costs and desire for increased functionality on a chip are driving semiconductor companies to consider SoC (System-on-a-chip) design. SoC offers the additional benefit of improving performance and design freedom. SoC designs are smaller, energy efficient and cheaper than the multi-chip solutions. Silicon manufacturing technology has improved to an extent where one can create a reliable chip with millions of transistors. Design of these complex systems, on the other hand, is taking longer and is much costlier even when the technology allows integration of the million transistor chips. Keeping these design costs low and reducing development cycle time is vital for any chip design company. Hence, companies need to delicately balance the design costs versus benefits for SoC design. Design turn-around time (TAT) even for large complex designs has been significantly improved by EDA tools despite the complexity added by the ever shrinking device geometries. However, other non technical issues and external dependencies in SoC design such as working with multi-disciplinary design teams, external IP (Intellectual Property) vendors, Electronic Design Automation (EDA) tool vendors and IP protection issues increase the risk of missing project goals and timeline. This paper will address both the technical and non-technical issues that arise when moving to SoC design and provide recommendations on how to address some of the non-technical issues involved. / text

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

Optical and electrical properties of solids have a close relationship with their dimensionalities. In this thesis, optical properties of several direct bandgap materials with different dimensionalities were investigated in detail. In three dimensional bulk zinc oxide (ZnO) single crystal, two electron satellite transition (TES) was examined in terms of a radiative Auger effect. On the basis of experimental spectral data, a model was proposed to interpret temperature dependence of its integrated intensity. Meanwhile, the phonon coupling with various excitonic transitions were discussed as a function of temperature in bulk ZnO single crystals. Being as a new family of two dimensional materials, monolayers of transition metal dichalcogenides (TMDCs) have received an increasing research interest in the past few years because they have been proved to be direct bandgap semiconductors. Light emission properties of tungsten sulfide (WS2) monolayers were characterized by using excitation power dependent photoluminescence (PL) technique. Two kinds of emission mechanisms, namely band-edge free excitonic transition and localized-states ensemble emission, were revealed in WS2 monolayers. Meanwhile, PL and Raman mapping for WS2 monolayers were conducted. It was found the relative intensity of inter-plane vibration mode with respect to in-plane mode is critical for monolayer identification with Raman spectroscopic technique and PL mapping can yield more information on the uniformity and quality of the samples. In the third part of this degree research, various low dimensional nanostructures of WS2, ZnO and GaN were studied. WS2 nanotubes were found to show interesting Raman light scattering features, while ZnO nanorods prepared by vapor phase transport method were revealed to have distinctive light emission properties. Finally, by focused ion beam milling, GaN and ZnO nano-array were fabricated. Surface vibration mode was firmly demonstrated to exist in these nanostructures with optical studies and theoretical analysis. / published_or_final_version / Physics / Doctoral / Doctor of Philosophy