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Since the outset of IC Semiconductor market there has been a gap between its design and manufacturing communities. This gap continued to grow as the device geometries started to shrink and the manufacturing processes and tools got more complex. This gap lowered the manufacturing yield, leading to higher cost of ICs and delay in their time to market. It also impacted performance of the ICs, impacting the overall functionality of the systems they were integrated in. However, in the recent years there have been major efforts to bridge the gap between design and manufacturing using software solutions by providing closer collaborations techniques between design and manufacturing communities. The root cause of this gap is inherited by the difference in the knowledge and skills required by the two communities. The IC design community is more microelectronics, electrical engineering and software driven whereas the IC manufacturing community is more driven by material science, mechanical engineering, physics and robotics. The cross training between the two is almost nonexistence and not even mandated. This gap is deemed to widen, with demand for more complex designs and miniaturization of electronic appliance-products. Growing need for MEMS, 3-D NANDS and IOTs are other drivers that could widen the gap between design and manufacturing. To bridge this gap, it is critical to have close loop solutions between design and manufacturing This could be achieved by SMART automation on both sides by using Artificial Intelligence, Machine Learning and Big Data algorithms. Lack of automation and predictive capabilities have even made the situation worse on the yield and total turnaround times. With the growing fabless and foundry business model, bridging the gap has become even more critical. Smart Manufacturing philosophy must be adapted to make this bridge possible. We need to understand the Fab-fabless collaboration requirements and the mechanism to bring design to the manufacturing floor for yield improvement. Additionally, design community must be educated with manufacturing process and tool knowledge, so they can design for improved manufacturability. This study will require understanding of elements impacting manufacturing on both ends of the design and manufacturing process. Additionally, we need to understand the process rules that need to be followed closely in the design phase. Best suited SMART automation techniques to bridge the gap need to be studied and analyzed for their effectiveness.

<p>The continuous reduction of feature size in silicon-based electronic integrated circuits (ICs) is accompanied by devastating propagation delay time and power consumption that have become known as the “Interconnect Bottleneck”. Optical interconnection is a proposed solution that is poised to revolutionize the data transmission both within and between ICs. By forming the optical transmission and functional elements from silicon, they can be monolithically incorporated with standard ICs using the established CMOS (Complementary Metal Oxide Semiconductor) infrastructure with minimal incremental cost. A key required functional element is the photodetector, which provides optical-toelectrical conversion of signals. In this thesis, a method of achieving such conversion is explored, which uses the optical absorption at 1550 nm wavelengths provided by lattice defects. The physics governing defect-enhanced silicon waveguide photodiode operation is described, and a device model is used to verify the posited detection process and propose design improvements. The model was used to design a novel photodetector structure using a waveguide formed by the LOCOS (LOCal Oxidation of Silicon) process with a poly-silicon self-aligned contact. The fabricated device exhibited a responsivity of 47 mA/W, providing an improvement over previous devices of similar dimensions, although were ultimately limited by the quality of the poly-silicon/silicon interface. A sub-micron waveguide photodiode fabrication process using electron-beam lithography was developed, which produced photodiodes with responsivities of 490 mA/W. This process was used to integrate photodiodes onto micro-ring resonators, which exhibit resonant enhanced photocurrent. The physics of this enhancement were explored, and found to produce a 50 μm long resonant photodiode of responsivity equal to that of a 3 mm long non-resonant photodiode. Lastly, the integration of such sub-micron photodiodes as functioning power monitors throughout photonic circuits was demonstrated as a means to characterize and tune micro-rings during operation.</p> / Doctor of Philosophy (PhD)

<p>Gallium nitride (GaN) nanowires are high-performance materials with wide, direct bandgaps and superior electronic properties. Although their properties make them of great interest for next-generation technologies, widespread adoption has been limited by expensive production processes. Here, the results of growing GaN nanowires via DC magnetron sputtering at different temperatures and using different metal catalysts are reported.</p> <p>A new substrate heater was designed to minimize contamination from the heater filament and increase the substrate temperature window to in excess of 800°C. Sixteen-mm² (111) silicon samples had one-to-four nm of a metal catalyst deposited on them using evaporation. This metal catalyst layer (gold, platinum, or nickel) was employed to induce catalyst-assisted vapor-liquid-solid nanowire growth. GaN was deposited via a reactive nitrogen DC magnetron sputtering system. Surface morphology and composition were analyzed using both scanning and transmission electron microscopy. Energy-dispersive x-ray spectroscopy (EDS) and electron energy loss spectroscopy were used to measure the presence of gallium and nitrogen in the resulting nanowires, respectively.</p> <p>This furnace significantly reduced tungsten contamination to below the detectable levels of EDS. GaN nanowires were present on gold-catalyzed samples only in the gold-covered region of the silicon substrate exposed to a gallium flux. Nanowire morphology improved as temperature was elevated, but it did so at the cost of lower areal density. Conversely, platinum-coated samples yielded fewer nanowires than their gold-coated counterparts. Samples that had nickel deposited on them displayed the best GaN nanowire growths. They had the best surface morphologies, had negligible oxygen concentrations, and were single crystalline.</p> / Master of Applied Science (MASc)

OPTICAL CHARACTERIZATION OF INGAN HETEROSTRUCTURES FOR BLUE LIGHT EMITTERS AND VERTICAL CAVITY LASERS: EFFICIENCY AND RECOMBINATION DYNAMICS By Serdal Okur, Ph.D. A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University. Virginia Commonwealth University, 2014. Major Director: Ümit Özgür, Associate Professor, Electrical and Computer Engineering This thesis explores radiative efficiencies and recombination dynamics in InGaN-based heterostructures and their applications as active regions in blue light emitters and particularly vertical cavities. The investigations focus on understanding the mechanism of efficiency loss at high injection as well as developing designs to mitigate it, exploring nonpolar and semipolar crystal orientations to improve radiative efficiency, integration of optimized active regions with high reflectivity dielectric mirrors in vertical cavity structures, and achieving strong exciton-photon coupling regime in these microcavities for potential polariton lasing. In regard to active regions, multiple double heterostructure (DH) designs with sufficiently thick staircase electron injection (SEI) layers, which act as electron coolers to reduce the overflow of hot electrons injected into the active region, were found to be more viable to achieve high efficiencies and to mitigate the efficiency loss at high injection. Such active regions were embedded in novel vertical cavity structure designs with full dielectric distributed Bragg reflectors (DBRs) through epitaxial lateral overgrowth (ELO), eliminating the problems associated with semiconductor bottom DBRs having narrow stopbands and the cumbersome substrate removal process. Moreover, the ELO technique allowed the injection of carriers only through the high quality regions with substantially reduced threading dislocation densities compared to regular GaN templates grown on sapphire. Reduced electron-hole wavefunction overlap in polar heterostructures was shown to hamper the efficiency of particularly thick active regions (thicker than 3 nm) possessing three-dimensional density of states needed for higher optical output. In addition, excitation density-dependent photoluminescence (PL) measurements showed superior optical quality of double heterostructure (3 nm InGaN wells) active regions compared to quantum wells (2 nm InGaN wells) suggesting a minimum limit for the active region thickness. Therefore, multiple relatively thin but still three dimensional InGaN active regions separated by thin and low barriers were found to be more efficient for InGaN light emitters. Investigations of electroluminescence from light emitting diodes (LEDs) incorporating multi DH InGaN active regions (e.g. quad 3 nm DH) and thick SEIs (two 20 nm-thick InGaN layers with step increase in In content) revealed higher emission intensities compared to LEDs with thinner or no SEI. This indicated that injected electrons were cooled sufficiently with thicker SEI layers and their overflow was greatly reduced resulting in efficient recombination in the active region. Among the structures considered to enhance the quantum efficiency, the multi-DH design with a sufficiently thick SEI layer constitutes a viable approach to achieve high efficiency also in blue lasers. Owing to its high exciton binding energy, GaN is one of the ideal candidates for microcavities exploiting the strong exciton-photon coupling to realize the mixed quasiparticles called polaritons and achieve ideally thresholdless polariton lasing at room temperature. Angle-resolved PL and cathodoluminescence measurements revealed large Rabi splitting values up to 75 meV indicative of the strong exciton-photon coupling regime in InGaN-based microcavities with bottom semiconductor AlN/GaN and a top dielectric SiO2/SiNxDBRs, which exhibited quality factors as high as 1300. Vertical cavity structures with all dielectric DBRs were also achieved by employing a novel ELO method that allowed integration of a high quality InGaN cavity active region with a dielectric bottom DBR without removal of the substrate while forming a current aperture through the ideally defect-free active region. The full-cavity structures formed as such were shown to exhibit clear cavity modes near 400 and 412 nm in the reflectivity spectrum and quality factors of 500. Although the polar c-plane orientation has been the main platform for the development of nitride optoelectronics, significant improvement of the electron and hole wavefunction overlap in nonpolar and semipolar InGaN heterostructures makes them highly promising candidates for light emitting devices provided that they can be produced with good crystal quality. To evaluate their true potential and shed light on the limitations put forth by the structural defects, optical processes in several nonpolar and semipolar orientations of GaN and InGaN heterostructures were investigated. Particularly, stacking faults were found to affect significantly the optical properties, substantially influencing the carrier dynamics in nonpolar (1-100), and semipolar (1-101) and (11-22)GaN layers. Carrier trapping/detrapping by stacking faults and carrier transfer between stacking faults and donors were revealed by monitoring the carrier recombination dynamics at different temperatures, while nonradiative recombination was the dominant process at room temperature. Although it is evident that nonpolar (1-100)GaN and semipolar (11-22)GaN require further improvement of material quality, steady-state and time-resolved PL measurements support that (1-101)-oriented GaN templates and InGaN active regions exhibit optical performance comparable to their highly optimized polar c-plane counterparts, and therefore, are promising for vertical cavities and light emitting device applications.

This thesis explores the improvement of quantum efficiencies for InGaN/GaN heterostructures and their applications in light-emitting diodes (LEDs) and vertical cavity surface-emitting lasers (VCSELs). Different growth approaches and structural designs were investigated to identify and address the major factors limiting the efficiency. (1) Hot electron overflow and asymmetrical electron/hole injection were found to be the dominant reasons for efficiency degradation in nitride LEDs at high injection; (2) delta p-doped InGaN quantum barriers were employed to improve hole concentration inside the active region and therefore improve hole injection without sacrificing the layer quality; (3) InGaN active regions based on InGaN multiple double-heterostructures (DHs) were developed to understand the electron and hole recombination mechanisms and achieve high quantum efficiency and minimal efficiency droop at high injection; (4) the effect of stair-case electron injectors (SEIs) has been investigated with different active region designs and SEIs with optimized thickness greatly mitigated electron overflow without sacrificing material quality of the active regions. The active regions showing promising performance in LEDs were incorporated into VCSEL designs. Hybrid VCSEL structures with bottom semiconductor AlN/GaN and a top dielectric SiO2/SiNx DBRs have been investigated, and quality factors as high as 1300 have been demonstrated. Finally, VCSEL structures with all dielectric DBRs have been realized by employing a novel ELO-GaN growth method that allowed integration of a high quality InGaN cavity active region with a dielectric bottom DBR without removal of the substrate while forming a current aperture through the ideally dislocation-free region. The full-cavity structures formed as such exhibited quality factors 500 across the wafer.

Este trabalho apresenta a compensação e calibração de sensores de pressão piezoresistivos com a utilização de resistores de alta precisão. Para que tal objetivo fosse cumprido, foi necessária a caracterização do sensor com relação aos parâmetros térmicos e elétricos. Além disso, foi definida uma metodologia com a qual se obteve os tempos necessários para aquisição dos dados com relação ao valor de precisão requisitada. Os resultados mostram que os valores dos resistores são dependentes da alimentação fornecida ao sensor e que a variação da tensão de saída, com relação a uma média, tem caráter parabólico. A curva do tempo de estabilização para aquisição de dados tem formato assintótico. Com a compensação e calibração tivemos uma diminuição na tensão de offset de cerca de 97% e compensação térmica com cerca de 70% para a tensão de fundo de escala, porém com isso foi reduzido 8% no valor da sensibilidade. / This work presents the compensation and calibration of piezoresistive pressure sensors with the use of precision resistors. For this objective to be met was necessary to characterize the sensor with respect to thermal and electrical parameters. Also it was defined a methodology with which they obtained the time required for data acquisition based on the value of precision required. The results show that the values of resistors are dependent on power supplied to the sensor and the variation of the output voltage with respect to an average has a parabolic feature. The curve of the settling time for data acquisition format is asymptotic. With the compensation and calibration, a decrease in the offset voltage of about 97% was observed and temperature was compensated with 70% for full scale, however, the sensitivity was reduced in 8%.

Introdução: Nos dias de hoje, possibilitar o acesso à informação com os mais diferentes meios de comunicação torna-se fundamental e ao mesmo tempo desafiador. Deste modo, qualquer estratégia utilizada é importante. A educação a distancia figura como a estratégia facilitadora para o acesso de informação, informação esta que poderá repercutir na qualidade de vida do indivíduo se consideramos, por exemplo, os programas de capacitação com a temática que envolve saúde auditiva. Objetivo: Este estudo teve por objetivo criar uma rede de aprendizagem colaborativa como modelo de educação em saúde auditiva, por meio da Teleducação Interativa e analisar a eficácia do mesmo. Metodologia: o estudo foi realizado em 4 escolas da rede pública da cidade de Bauru. Participaram dessa proposta 38 alunos do 9o ano, de ambos os sexos, na faixa etária entre 14 e 15 anos. O programa de capacitação apresentou duração média de 4 meses em cada escola e foi dividido em 2 etapas, a primeira englobando a elaboração dos módulos educacionais, desenvolvimento do programa de capacitação, atividades presenciais, atividades a distancia e atividades práticas na temática de saúde auditiva e, a segunda etapa consistiu na avaliação da eficácia do programa. Foi desenvolvido o Cybertutor sobre o tema saúde auditiva, com o intuito de complementar o aprendizado, disponibilizado na internet, e os participantes tinham livre acesso. A atividade presencial continha a apresentação de aulas expositivas, conteúdos gráficos e audiovisuais. Na atividade a distância, o conteúdo educacional foi apresentado aos alunos por meio da Teleducação Interativa. Nesta fase, os alunos tiveram acesso ao Cybertutor. Após o período de capacitação, os estudantes intitulados Jovens Doutores, realizaram a atividade prática tendo como proposta a multiplicação do conhecimento adquirido. Para mensurar a eficácia do programa de capacitação foram aplicados os seguintes instrumentos: Questionário Situação-Problema, Escala Lickert de Atitudes Sociais em Relação à inclusão (ELASI) e Ficha de Pesquisa Motivacional (FPM). Resultados: Os resultados das avaliações pré e pós-teste do Questionário Situação-Problema e da ELASI, revelaram que o programa de capacitação desenvolvido foi eficaz, pois proporcionou à construção do conhecimento e o desenvolvimento de atitudes mais favoráveis em relação à inclusão. A FPM demonstrou um índice de motivação em relação à participação altamente positivo, avaliando o programa como Impressionante. Conclusões: O presente estudo permitiu concluir que foi desenvolvido um programa educacional utilizando a Teleducação Interativa como modelo de educação em saúde auditiva. Este programa foi eficaz, pois proporcionou o aprendizado dos alunos das escolas participantes. A elaboração deste modelo de capacitação alcançou um índice de motivação em relação à participação altamente positivo. Mostrou ser uma proposta eficiente de educação na temática sobre a saúde auditiva, podendo ser considerada uma importante estratégia de consolidação da inclusão do deficiente auditivo na comunidade. Na avaliação realizada nas escolas participantes do projeto, a utilização da metodologia do programa Projeto Jovem Doutor estimulou e motivou os participantes a realizarem a multiplicação do conhecimento adquirido, portanto, evidenciou ser um programa eficaz de educação em saúde auditiva, podendo ser utilizado para a capacitação de outras populações. / Introduction: Nowadays, providing access to information with the most different types of media becomes crucial and challenging at the same time. Therefore, any strategy used is important. The distance education appears as a strategy for facilitating access to information, this information that may impact on the quality of life for the individual to consider, for example, programs with the theme that involves hearing health. Objective: This study aimed to create a network of collaborative learning as an educational model for hearing health, tele-education through interactive and analyze the effectiveness of it. Methodology: The study was conducted in four public schools in Bauru. Thirty eight 9th grader students participated in this proposal , both male and female, between 14 and 15 years old. The training program had a mean duration of 4 months in each school and was divided into 2 phases, the first covering the development of educational modules, development of the training program, classroom activities, distance activities and practical activities in the thematic hearing health and the second step was to assess the effectiveness of the program. There was a Cybertutor developed on the hearing health issue, in order to complement the learning available on the Internet, and participants had free access. The classroom activity contained presentation of lectures, graphics and audiovisual content. In the distance learning activity, the educational content was presented to the students through interactive tele-education. At this stage, students had access to Cybertutor. After the training period, the students titled \"Young Doctors\", carried out the practical activity proposing multiplication of the acquired knowledge. To measure the effectiveness of the training program the following instruments were applied: Questionnaire Situation-Problem, Lickert Scale of Social Attitudes Toward Inclusion (ELASI) Form and Motivational Research (FPM). Results: The results of pre-and post-test of the questionnaire Situation- Problem and ELASI revealed that the training program developed was effective because it provided for the construction of knowledge and the development of more favorable attitudes toward inclusion. The FPM showed an index of motivation in relation to highly positive participation, evaluating the program as \"impressive\". Conclusions: This study concluded that an educational program using the Interactive Tele-education as hearing health education model was developed . This program was effective because it provided the learning of students in the participating schools . The development of this training model achieved an index of motivation in relation to highly positive participation. It is an efficient education proposal on the issue about hearing health and may be considered an important strategy to consolidate the inclusion of the hearing impaired community. In the evaluation of the project in the participating schools, the use of the methodology of program design Young Doctor stimulated and motivated the participants to perform the multiplication of the knowledge acquired thus proven to be an effective program of health education and can be used for training other populations.