Bibliography: pages 51-54. / The microstructure of different types of industrially produced heating elements was examined and an x-ray diffraction method was devised to determine the relative amounts of α- and β-silicon carbide present in these materials. It was confirmed that the α- to β-silicon carbide transformation occurs during heat treatment, because of the influence of the nitrogen atmosphere in the furnace. The fabrication parameters important in the manufacture of heating elements were investigated. Porous sintered silicon carbide samples were made using different proportions of grit sizes and various firing schedules. Both resistivity and crushing strength were determined. It was found that the resistivity is dependent upon degree of sintering (indicated by crushing strength) as well as the packing density of the porous body.

In Canada, many remote communities rely on diesel power for the majority of their energy needs, which can cause negative ecological and health impacts while limiting economic development. Bifacial photovoltaics present an alternative to diesel power. With high average latitudes, these communities show potential for large bifacial gains due to high albedo caused by snow and a high fraction of diffuse light; however, high-latitude conditions deviate from standard test conditions, with low average temperatures, light incident from many directions, and high average air masses, resulting in increased energy yield prediction uncertainty. This thesis describes the performance of bifacial silicon heterojunction cells and modules under high-latitude operating conditions, including high angles of incidence and high air masses. Optical losses in the cell and module are described, and module characteristics are incorporated in DUET, the SUNLAB's energy yield prediction software, as an incidence angle modifier and air mass modifier. The percentage change in energy yield when considering air mass is shown to increase with increasing latitude: for a single-axis-tracked installation, the annual difference in energy yield is 0.5% in a low-latitude location (33°N), and more than 2.5% in a high-latitude location (69°N). Air mass correction is demonstrated to improve energy yield prediction accuracy compared to the absence of spectral correction. This work improves energy yield prediction accuracy for high-latitude locations, facilitating adoption of solar energy in diesel-dependent remote communities in Canada and abroad.

An economically reliable technique for the synthesis of silicon nanowire was developed using silicon chloride as source material. The 30-40 micron long nanowires were found to have diameters ranging from 40 – 100 nm. An amorphous oxide shell covered the nanowires, post-growth. Raman spectroscopy confirmed the composition of the shell to be silicon-dioxide. Photoluminescence measurements of the as-grown nanowires showed green emission, attributed to the presence of the oxide shell. Etching of the oxide shell was found to decrease the intensity of green emission. n-type doping of the silicon nanowires was achieved using antimony as the dopant. The maximum dopant concentration was achieved by post-growth diffusion. Intrinsic nanowire parameters were determined by implementation of the as-grown and antimony doped silicon nanowires in field effect transistor configuration.

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Atmospheric turbulence in free space optical satellite downlinks negatively impacts link availability and bit error rate. These effects can be mitigated using a compensation system capable of measuring the incoming wavefront distortion and applying a suitable correction to the received signal. The traditional solution based on adaptive optics and the Shack-Hartmann wavefront sensor has limitations in bandwidth, system complexity, size, weight, and power consumption. Signal correction can also be accomplished using a novel single-chip silicon photonic solution. This work introduces a four-arm grating coupler structure acting as a wavefront sensing element that emulates the performance of the Shack-Hartmann wavefront sensor by giving local tip and tilt estimation. FDTD simulations and measurements have confirmed the presence of a monotonic relationship between incident angle, polarization, and coupler output which can be converted to phase estimation through a reconstruction algorithm. An array of four-arm couplers on a silicon photonic chip provides enough sampling to fully reconstruct the wavefront, providing benefits over traditional solutions such as higher bandwidth, reduced size and weight, and reduced cost. Scaling up the results of this work to a full device could provide a solution for free space optical satellite to ground links in remote and rural communities across Canada and around the world. / Thesis / Master of Applied Science (MASc)

This work demonstrates design of analog circuit blocks using radiation-hardened and temperature tolerant silicon carbide enhancement and depletion JFET. Most of the work to date in silicon carbide is focused on CMOS like circuits, which are less temperature tolerant, compared to JFETs. In this work, efforts have been made to accurately model silicon carbide depletion and enhancement mode n-JFETs. I-V characteristics of the models were simulated for different values of channel thickness and doping concentration. Analog circuit building blocks such as current mirrors and sources are presented for both enhancement mode and depletion mode JFETs at different temperatures. A source coupled differential amplifier was designed using depletion mode silicon carbide n-JFETs. Various differential amplifier specifications such as Voltage swing, input common mode range (ICMR), differential gain, common mode gain and Common mode rejection ratio (CMRR) are simulated at room temperature and at 673K.

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