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<p> This thesis demonstrates two concepts, one a viable fabrication process for an FeCr alloy supported solid oxide fuel cell (SOFC), and second, the use of CozMn04 (spinel)as the cathode material. Ni/YSZ and YSZ layers were used as anode and electrolyte respectively. The fabrication process consisted of tape casting of iron and chromium oxide powders for the support, dip coating of NiO-YSZ-Fe30 4-Crz03-C and YSZ as anode and electrolyte respectively, synthesis of CozMn04 from Co304 and MnOz as the , cathode material and finally screen printing of the CozMn04 cathode. The support, the anode, and the electrolyte were co-fired at 1350°C in air for 10 hours, then CozMn04 was screen printed and the cell was again fired at 1250°C for 4 hours in air. The complete cell was reduced in pure Hz at 950°C for 10 hours to convert the major part of support into Fe-Cr alloy, leaving approximately 20% unreduced FeCrz04. </p> <p> The fully fabricated cell was tested at 820°C using 7% Hz, 93% Nz as the fuel and air as the oxidant. The Co2MnO4 cathode which reduced to MnO + Co during the final processing stage was recovered in-situ at the start of the test. Pt mesh was used for current collection. The power density was in the range of 80-120 mW/cm2. </p> / Thesis / Master of Applied Science (MASc)

<p> In the current research, use of p-n junction GaAs nanowires (NWs) grown by gas source molecular beam epitaxy on GaAs (111) B substrates for the fabrication of flexible solar cells are reported. The solar cells were fabricated by embedding the NWs in a polymer matrix (SU8 2), followed by ohmic contact formation to the tops of the NWs as well as the rear side of the substrate. I-V characteristic curves were obtained by illuminating the solar cells using a solar simulator, indicating a photovoltaic effect. NWs were also detached from the substrate by different methods and successfully transferred onto a flexible substrate for potential use as solar cells. Scanning electron microscopy was used throughout the research for characterization and optimization of the fabrication processes including NW embedment, removal from the substrate, and contact formation.</p> / Thesis / Master of Applied Science (MASc)

Single-pass frequency conversion by a nonlinear optical crystal is an attractive method to generate coherent radiation in various spectral domains from ultraviolet to mid-infrared. Wavelength converters based on quasi-phase matched (QPM) periodically poled lithium niobate (PPLN) have proved to be important wavelength conversion devices for many useful applications. This thesis develops a novel integration design for temperature controlling and temperature wavelength tuning of a QPM-PPLN waveguide wavelength converter. A Cr/Pt/Au thin film alloy layer is deposited on a PPLN device with a polymer buffer layer to work as a micro-heater and a temperature sensor at the same time. The temperature of the device can be tailored by applying current to the micro-heater layer, which changes the effective period of the QPM grating and thus the QPM wavelength through the thermal optical effect (TOE). The device's temperature can be monitored by measuring the resistance change of the alloy layer. Micro-heater design and mode profile simulation are involved in the thesis. The entire device fabrication process is introduced. Both electrical and optical features of the device are characterized and discussed. In contrast to the conventional temperature tuning method based on a bulky oven, the proposed design has some excellent characteristics such as compact package size and low power consumption. / Thesis / Master of Applied Science (MASc)

The growth optimization and fabrication of 980nm quantum well (QW) lasers is presented. Photoluminescence (PL) spectroscopy is used to determine the optimized growth conditions for the QWs. The results are presented for optimization of both growth temperature and group V overpressure. Broad area lasers, with active regions grown at and around optimized QW growth conditions, are fabricated and characterized under pulsed conditions. These results are used to determine the optimum growth conditions for a ridge waveguide (RWG) laser structure. Once grown, RWG lasers are fabricated and characterized under continuous wave (CW) conditions. External quantum efficiencies as high as 71 % and cavity losses as low as 5.2 cm-1 are achieved. / Thesis / Master of Engineering (ME)

Silicon photonics provides an environmentally sustainable pathway to a more robust data infrastructure. To compensate for optical power losses, methods of amplification are required; specifically, amplifiers that can fit in a small footprint for applications in data centres. Semiconductor optical amplifiers (SOA) provide such a solution, and can be fabricated using III-V ternary or quaternary materials to enhance optical signals through a device on the scale of most CMOS components. This research sought to fabricate an InGaAsP multiple quantum well semiconductor optical amplifier using the facilities in McMaster University’s Centre for Emerging Device Technologies (CEDT). A ridge waveguide laser diode was first fabricated and validated, then altered by applying an anti-reflective coating to the waveguide facets to suppress reflections in the Fabry-Perot cavity in an attempt to create an SOA. The design process and fabrication methodology are explained, including an analysis of failed methodologies. Characterization measurement techniques are then detailed for the fabricated devices. Finally, the performance of the devices is presented, and future steps are suggested for improving the fabrication process to enhance device characteristics. The fabricated laser diodes produced an output power in excess of 20 mW at a peak wavelength near 1580 nm. The subsequently coated devices proved difficult to measure, displaying a maximum of 0 dB or 1 dB gain when checked for amplification, with suspicions that output loss (and therefore gain) was higher than measured. The coated devices exhibited gain saturation between -10 and 0 dBm of input power. Owing to the shapes of their characteristic curves, it was determined that SOA devices were successfully created. / Thesis / Master of Applied Science (MASc)