The Emitter Controlled Thyristor (ECT) is a new MOS-Gated Thyristor (MGT) that combines the ease of a MOS gate control with the superior current carrying capability of a thyristor structure for high-power applications. An ECT is composed of an emitter switch in series with the thyristor, an emitter-short switch in parallel with the emitter junction of the thyristor, a turn-on FET and the main thyristor structure. Numerical analysis shows that the ECT also offers superior high voltage current saturation capability even for high breakdown voltage ratings. Two different ECT structures are investigated in this research from numerical simulations to experimental fabrications. A novel ECT structure that utilizes IGBT compatible fabrication process was proposed. The emitter short FET, emitter switch FET and turn-on FET are all integrated with a high voltage thyristor. Numerical simulation results show that the ECT has a better conductivity modulation than that of the IGBT and at the same time exhibits superior high voltage current saturation capability, superior FBSOA and RBSOA. The technology trade-off between turn-off energy loss and forward voltage drop of the ECT is also better than that of the IGBT because of the stronger conductivity modulation. A novel self-aligned process is developed to fabricate the device. Experimental characteristics of the fabricated ECT devices show that the ECT achieves lower forward voltage drop and superior high voltage current saturation capability. A Hybrid ECT (HECT) structure was also developed in this research work. The HECT uses an external FET to realize the emitter switching function, hence a complicated fabrication issue was separated into two simple one. The cost of the fabrication decreases and the yield increases due to the hybrid integration. Numerical simulations demonstrate the superior on-state voltage drop and high voltage current saturation capability. A novel seven-mask process was developed to fabricate the HECT. Experimental results show that the HECT could achieve the lower forward voltage drop and superior current saturation capability. The resistive switching test was carried out to demonstrate the switching characteristics of the HECT. / Master of Science

The Emitter Controlled Thyristor (ECT) is a new MOS-Gated Thyristor (MGT) that combines the ease of a MOS gate control with the superior current carrying capability of a thyristor structure for high-power applications. An ECT is composed of an emitter switch in series with the thyristor, an emitter-short switch in parallel with the emitter junction of the thyristor, a turn-on FET and the main thyristor structure. Numerical analysis shows that the ECT also offers superior high voltage current saturation capability even for high breakdown voltage ratings. Two different ECT structures are investigated in this research from numerical simulations to experimental fabrications. A novel ECT structure that utilizes IGBT compatible fabrication process was proposed. The emitter short FET, emitter switch FET and turn-on FET are all integrated with a high voltage thyristor. Numerical simulation results show that the ECT has a better conductivity modulation than that of the IGBT and at the same time exhibits superior high voltage current saturation capability, superior FBSOA and RBSOA. The technology trade-off between turn-off energy loss and forward voltage drop of the ECT is also better than that of the IGBT because of the stronger conductivity modulation. A novel self-aligned process is developed to fabricate the device. Experimental characteristics of the fabricated ECT devices show that the ECT achieves lower forward voltage drop and superior high voltage current saturation capability. A Hybrid ECT (HECT) structure was also developed in this research work. The HECT uses an external FET to realize the emitter switching function, hence a complicated fabrication issue was separated into two simple one. The cost of the fabrication decreases and the yield increases due to the hybrid integration. Numerical simulations demonstrate the superior on-state voltage drop and high voltage current saturation capability. A novel seven-mask process was developed to fabricate the HECT. Experimental results show that the HECT could achieve the lower forward voltage drop and superior current saturation capability. The resistive switching test was carried out to demonstrate the switching characteristics of the HECT. / Master of Science

Specific emitter identification is a technology used to uniquely identify a class of wireless devices, and in some cases a single device. Minute differences in the implementation of a wireless communication standard from one device manufacturer to another make it possi- ble to extract a wireless "fingerprint" from the transmitted signal. These differences may stem from imperfect radio frequency (RF) components such as filters and power amplifiers. However, the problem of identifying a wireless device through analysis of these key signal characteristics presents several difficulties from an algorithmic perspective. Given that the differences in these features can be extremely subtle, in general a high signal to noise ratio (SNR) is necessary for a sufficient probability of correct detection. If a sufficiently high SNR is not guaranteed, then some from of identification algorithm which operates well in low SNR conditions must be used. Cyclostationary analysis offers a method of specific emitter iden- tification through analysis of second order spectral correlation features which can perform well at relatively low SNRs. The eigenvector/eigenvalue decomposition (EVD) is capable of separating principal components from uncorrelated gaussian noise. This work proposes a technique of specific emitter identification which utilizes the principal components of the EVD of the spectral correlation function which has been arranged into a square matrix. An analysis of this EVD-based SEI technique is presented herein, and some limitations are identified. Analysis is constrained to orthogonal frequency division multiplexing (OFDM) using the IEEE 802.16 specification (used for WiMAX) as a guideline for a variety of pilot arrangements. / Master of Science

<p dir="ltr">Quantum photonics is one of the leading platforms to realize quantum information technologies. Quantum emitters embedded in host materials which can readily form photonic circuitry elements have received significant research interest in recent years for on-chip quantum information processing applications. In this work, we report on the discovery of bright, stable, and linearly polarized quantum emitters in SiN films with room temperature single photon generation. We suggest that the emission originates from a specific defect center in SiN because of the narrow wavelength distribution of the observed luminescence peak.</p><p dir="ltr">We further probe these emitters’ fundamental photophysical properties through measurements of optical transition wavelengths, linewidths, and photon antibunching as a function of temperature. Important insight into the potential for lifetime-limited linewidths is provided through measurements of inhomogeneous and temperature-dependent broadening of the zero-phonon lines. At 4.2K, spectral diffusion was found to be the main broadening mechanism, while spectroscopy time series revealed zero-phonon lines with instrument-limited linewidths.</p><p dir="ltr">Along with the optical properties of the quantum emitters, we study their formation mechanisms by investigating the effects of sample composition and thermal annealing parameters. From these measurements, we gain critical insight into the fundamental nature of the quantum emitters in SiN, as well as the dependence of their photophysical properties on the changes in the host material. Additionally, we explore alternative SiN fabrication approaches and the optical properties of the SiN films developed with these techniques. We then investigate quantum emitter formation and hypothesize why the optical properties of the defects in each type of film differ.</p><p dir="ltr">Finally, we begin preliminary investigations into the possible existence of near-infrared (NIR) emitting defects in SiN, as well as single-photon electroluminescence from thin SiN-on-silica films embedded in p-n heterojunctions.</p><p dir="ltr">The single-photon emitters in SiN we have studied extensively in this work have the potential to enable scalable and low-loss integration of quantum light sources with a mature on-chip photonics platform.</p>

Radio Frequency Machine Learning (RFML) techniques for the classification tasks of Specific Emitter Identification (SEI) and Automatic Modulation Classification (AMC) have seen rapid improvements in recent years. The applications of SEI, a technique used to associate a received signal to an emitter, and AMC, a technique for determining the modulation scheme present within a transmission, are necessary for a variety of defense applications such as early warning systems and emitter tracking. Existing works studying SEI and AMC have sought to perform and improve classification through the use of various different machine learning (ML) model architectures. In ideal conditions, these efforts have shown strong classification results, however, when robust real-world data is applied to these models, performance notably decreases. Further efforts, therefore, are required to understand why each of these models fails in adverse conditions. With this understanding, robust architectures that are able to maintain performance in the presence of various data conditions can be created. The work presented in this thesis seeks to improve upon SEI and AMC models by furthering the understanding of how certain model architectures fail under varying data conditions, then applies Transfer Learning (TL) and Ensemble Learning techniques in an effort to mitigate discovered failures and improve the applicability of trained models to various types of data. Each of the approaches presented in this work utilize real-world datasets, collected in a way that emulate a variety of possible real life use conditions of RFML systems. Results show that existing AMC approaches are fairly robust to varying data conditions, while SEI approaches suffer a significant degradation in performance under conditions that differ than that used to train a given model. Further, TL and ensemble techniques can be utilized to improve the robustness of RFML models. This thesis helps isolate the rate and features of those SEI degradations, hopefully setting a foundation for future improvements. / Master of Science / Radio Frequency (RF) signals are produced by many different emitters encountered on a daily basis, including phones, networks, radar, and radios. These signals are used to transfer information from an emitter to a receiver, and contain a plethora of information that need be protected for defense practices in the RF domain. On the other hand, the information contained in these signals can be intercepted and utilized to discover information about potentially malicious transmissions. Two practices to determine information about received signals include Specific Emitter Identification (SEI), which relates an emitter to a received signal, and Automatic Modulation Classification (AMC), which determines the modulation scheme in which a signal is transmitted. A signal is made up of information, expressed in bits, and a modulation scheme is the method used to map those bits to express information. In recent years, Machine Learning (ML) techniques have been applied to SEI and AMC in an effort to improve the efficiency and accuracy results of classification. These ML approaches have shown high accuracy results when applied to data that is collected in the same environment as that used for training. When applied to data with different variables, however, model accuracy notably drops. This performance decrease motivates the need to discover more variables that negatively impact model performance, and further to create models that do not suffer from the same weaknesses. This work examines four different real-world variables that are common in deployed radio frequency machine learning (RFML) usage environments, and using the information learned about model failures, implements two approaches to create models that are more robust to variances in data. This work finds that model performance varies when exposed to variations in temperature, signal-to-noise ratio (SNR), training data quantity, and receiver hardware. Further, this work finds that Transfer Learning (TL) and Ensemble Learning can be used to create models that mitigate these discovered weaknesses.

The objective of the research in this thesis is to develop manufacturable high-efficiency silicon solar cells at low-cost through advanced cell design and technological innovations using industrially feasible processes and equipment on commercial grade Czochralski (Cz) large-area (239 cm2) silicon wafers. This is accomplished by reducing both the electrical and optical losses in solar cells through fundamental understanding, applied research and demonstrating the success by fabricating large-area commercial ready cells with much higher efficiency than the traditional Si cells. By developing and integrating multiple efficiency enhancement features, namely low-cost high sheet resistance homogeneous emitter, optimized surface passivation, optimized rear reflector, back line contacts, and improved screen-printing with narrow grid lines, 20.8% efficient screen-printed PERC (passivated emitter and rear cell) solar cells were achieved on commercial grade 239 cm2 p-type Cz silicon wafers.

Integrierte optoelektronische Anwendungen sind allgegenwärtig in moderner Technologie. Sie sind einerseits Schlüsselkomponenten in bekannten kommerziellen Produkten wie mobilen Geräten oder Flachbildschirmen, aber sie ermöglichen auch schnelle Netzwerke in Datenzentren. Um drängende Probleme im Zusammenhang mit dieser Technologie zu lösen, z.B. der hohe Energieverbrauch und die Verwendung und Rückgewinnung von seltenen Materialien, sucht die Forschung nach Alternativen. Insbesondere effiziente, nicht-lineare Prozesse werden benötigt, um Signale zu schalten. Einige vielversprechende Konzepte wurden in der Nanooptik vorgeschlagen. Diese basieren insbesondere auf plasmonischen Prozessen, die im Frequenzbereich von sichtbarem Licht stattfinden. Drei dieser Konzepte werden in dieser Arbeit diskutiert und untersucht. Teil 1 der Arbeit handelt von der konkreten Umsetzung eines Konzepts, das eine starke Interaktion zwischen einzelnen Quantenemittern und dem geführten Lichtfeld an metallischen Wellenleitern ausnutzt. Hierdurch können prinzipiell extrem schwache Lichtsignale zum Schalten verwendet werden. In Teil 2 wird die Miniaturisierung von Lasern untersucht. Kleine Lasersysteme finden schon heute Anwendungen in verschiedensten Bereichen der Optoelektronik. Diese Arbeit behandelt die kleinstmögliche Realisierung von Lasern, sogenannte Nanolaser, und untersucht deren Anwendbarkeit. Teil 3 widmet sich dem relativ neuen Materialsystem Graphen. In dieser Arbeit wird untersucht, in wie weit sich Graphen zur Manipulation von sichtbarem Licht verwenden lässt, beziehungsweise, in wie weit Graphen plasmonische Eigenschaften aufweist. Die Analyse der Konzepte liefert neue Erkenntnisse zu kontrovers diskutierten Themen bezüglich der Vorzüge und Nachteile der Miniaturisierung mit Hilfe der Plasmonik. Die Erkenntnisse geben des Weiteren klare Richtlinien zur Optimierung der Konzepte hin zu effizienteren und praktikableren Designs. / Integrated optoelectronic applications are omnipresent in modern technology. They are key constituents of familiar commercial products such as mobile devices and flat screens but also enable fast networks in data centers. In order to solve pressing problems induced by the technology, such as high power consumption and the use and recycling of rare materials, research tries to explore alternatives. In particular, there is a need for efficient, non-linear processes that could be employed for switching of signals. Some promising concepts have been proposed using nanooptics, especially based on plasmonic processes that take place at frequencies of visible light. Three of these concepts are discussed and investigated in this work. Part 1 of this work is about a concrete realization of a concept which makes use of a strong interaction between individual quantum emitters and guided light-fields of metallic waveguides. With this approach, in principle extremely weak light-signals can be sufficient for switching. In part 2 the miniaturization of lasers is investigated. Small laser-systems are already used today for a broad range of applications in optoelectronics. This works examines the smallest possible realization of lasers, so-called nanolasers, and investigates their applicability. Part 3 focuses on the relatively young material graphene. In this work it is investigated in which way graphene could be used for the manipulation of visible light, and accordingly, whether graphene features plasmonic properties. The analysis of these concepts provides new insights to controversial discussed topics with respect to the advantages and disadvantages of miniaturization with the help of plasmonics. Further, the findings give clear advice for the optimization of the concepts towards more efficient and practicable designs.

In the quest for reliable, repeatable and stable field electron emission that has commercial potential, whilst many attempts have been made, none yet has been truly distinguishable as being successful. Whilst I do not claim within this thesis to have uncovered the secret to success, fundamental issues have been addressed that concern the future directions towards achieving its full potential. An exhaustive comparison is made across the diverse range of materials that have, over the past 40-50 years, been postulated and indeed tested as field emitters. This has not previously been attempted. The materials are assessed according to the important metrics of turn on voltage, Eon, and maximum current density, Jmax, where low Eon and high Jmax are seen as desirable. The nano-carbons, carbon nanotubes (CNTs), in particular, perform well in both these metrics. No dependency was seen between the material work function and its performance as an emitter, which might have been suggested by the Fowler Nordheim equations. To address the issues underlying the definition of the local enhancement factor, β, a number of variations of surface geometry using CNTs were fabricated. The field emission of these emitters was measured using two different approaches. The first is a Scanning Electrode Field Emission Microscope, SAFEM, which maps the emission at individual locations across the surface of the emitter, and the parallel plate that is more commonly encountered in field emission measurements. Finally, an observed hysteretic behaviour in CNT field emission was explored. The field emitters were subjected to a number of tests. These included; in-situ residual gas analysis of the gas species in the emitter environment, a stability study in which the emitters were exposed to a continuing voltage loop for 50 cycles, differing applied voltage times to analyse the effects on the emitted current, and varying maximums of applied field in a search for hysteresis onset information. These studies revealed the candidate in causing the hysteresis is likely to be water vapour that adsorbs on the CNT surface. A six step model if the emission process was made that details how and when the hysteresis is caused.

BACKGROUND: DNA damage occurs as a consequence of both direct and indirect effects of ionizing radiation. The severity of DNA damage depends on the physical characteristics of the radiation quality, e.g., the linear energy transfer (LET). There are still contrary findings regarding direct or indirect interactions of high-LET emitters with DNA. Our aim is to determine DNA damage and the effect on cellular survival induced by (223)Ra compared to (188)Re and (99m)Tc modulated by the radical scavenger dimethyl sulfoxide (DMSO). METHODS: Radioactive solutions of (223)Ra, (188)Re, or (99m)Tc were added to either plasmid DNA or to PC Cl3 cells in the absence or presence of DMSO. Following irradiation, single strand breaks (SSB) and double strand breaks (DSB) in plasmid DNA were analyzed by gel electrophoresis. To determine the radiosensitivity of the rat thyroid cell line (PC Cl3), survival curves were performed using the colony formation assay. RESULTS: Exposure to 120 Gy of (223)Ra, (188)Re, or (99m)Tc leads to maximal yields of SSB (80 %) in plasmid DNA. Irradiation with 540 Gy (223)Ra and 500 Gy (188)Re or (99m)Tc induced 40, 28, and 64 % linear plasmid conformations, respectively. DMSO prevented the SSB and DSB in a similar way for all radionuclides. However, with the α-emitter (223)Ra, a low level of DSB could not be prevented by DMSO. Irradiation of PC Cl3 cells with (223)Ra, (188)Re, and (99m)Tc pre-incubated with DMSO revealed enhanced survival fractions (SF) in comparison to treatment without DMSO. Protection factors (PF) were calculated using the fitted survival curves. These factors are 1.23 ± 0.04, 1.20 ± 0.19, and 1.34 ± 0.05 for (223)Ra, (188)Re, and (99m)Tc, respectively. CONCLUSIONS: For (223)Ra, as well as for (188)Re and (99m)Tc, dose-dependent radiation effects were found applicable for plasmid DNA and PC Cl3 cells. The radioprotection by DMSO was in the same range for high- and low-LET emitter. Overall, the results indicate the contribution of mainly indirect radiation effects for each of the radionuclides regarding DNA damage and cell survival. In summary, our findings may contribute to fundamental knowledge about the α-particle induced DNA damage.

As variações de temperatura influenciam nas propriedades da água, especialmente na viscosidade. Este pode ser um fator significativo, que afeta a vazão dos emissores e consequentemente a uniformidade de aplicação. A necessidade de estudos que considerem o material das fitas gotejadoras, com diferentes tipos de emissores integrados e diferentes características construtivas, são importantes para entender a sensibilidade desses materiais quando submetidos a temperaturas de água distintas. Este experimento foi conduzido no Laboratório de Ensaios de Material de Irrigação (LEMI) do Departamento de Engenharia de Biossistemas da Escola Superior de Agricultura \"Luiz de Queiroz\" - ESALQ/USP. Foram avaliados cinco tipos de fitas gotejadoras, com diferentes emissores integrados e espessuras de parede. As curvas vazão-pressão para os diferentes materiais e espessuras de parede, apresentaram a mesma tendência, porém, com valores distintos dos parâmetros K e x para cada temperatura. Os valores de CVf para todos os materiais nas diferentes temperaturas apresentaram valores em conformidade com o estipulado por norma técnica. Não houve uma tendência específica dos valores de CVf e de IQR em relação à temperatura da água para os materiais avaliados. Para os emissores planos de fluxo turbulento, a vazão tende a diminuir com o incremento da temperatura, porém não significativamente (p>0,05). Para os emissores contínuos de fluxo turbulento, respostas diferentes foram obtidas, sendo que no emissor SilverDrip&#174; a vazão aumentou com o incremento da temperatura (p<0,05), enquanto no emissor Turbo Tape&#174;, a vazão diminuiu e as maiores variações de vazão ocorreram a partir de 60 kPa (p<0,05). Para o emissor moldado, a vazão aumentou (p<0,05) em função da temperatura, porém a maior variação ocorreu nas pressões mais baixas. Para nenhum dos materiais houve diferença significativa (p>0,05) na variação de vazão entre as espessuras de parede, indicando para os emissores estudados, que a espessura de parede não influencia na sensibilidade do emissor às variações de temperatura. Os resultados obtidos indicam que a sensibilidade do emissor em função da temperatura da água está associada ao valor do expoente de fluxo do emissor. / Temperature variations influence the properties of water, especially viscosity. This can be a significant factor, which affects the emitters\' discharge and consequently the uniformity of application. Studies analyzing drip tape material, types of integrated emitters and manufacturing characteristics are important to understand the sensitivity of these materials when operated in a range of values of water temperature. This experiment was carry out at the Laboratory of Tests of Irrigation Material (LEMI) of the Department of Engineering of Biosystems of the \"Luiz de Queiroz\" School of Agriculture - ESALQ / USP. Five types of drip tapes were evaluated, with various integrated emitters and wall thicknesses. The pressure-flow curves presented the same trend for the evaluated material, however, different values of the parameters K and x were found for each temperature. The CVf for all materials evaluating in a range of temperatures presented values in accordance with technical standards. There was no specific trend of the values of CVf neither IQR in relation to the water temperature. For the turbulent flow emitters, the discharge tends to decrease with increasing temperature, but not significantly (p>0.05). For the continuous emitters of turbulent flow, different responses were obtained, the emitter SilverDrip&#174; the discharge increased with the increase of the temperature (p<0,05), while for the emitter Turbo Tape&#174;, the discharge decreased and the greater variations of flow occurred from 60 kPa (p<0.05). For the emitter molded, the discharge increased (p<0.05) as a function of temperature, but the greater variation occurred in the lower pressures. For any of the materials, there was a significant difference (p>0.05) in the discharge variation comparing the wall thicknesses, indicating for the emitters studied, the wall thickness does not influence the discharge sensitivity to temperature variations. The results indicate that the sensitivity of the emitter as a function of the water temperature is associated with the exponent of emitter flow.