• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 35
  • 10
  • 9
  • 5
  • 3
  • 3
  • 2
  • 2
  • 1
  • Tagged with
  • 74
  • 18
  • 14
  • 14
  • 13
  • 12
  • 11
  • 10
  • 9
  • 9
  • 8
  • 8
  • 7
  • 7
  • 6
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

HOPE for the Science Education of Youth Involved with the Justice System

Singh, Diandra 14 January 2022 (has links)
Equitable schooling requires that all students are able to participate, including those who are involved in the justice system. However, schools for youth who are in custody or in treatment are presented with challenges that may inhibit offering their student body science courses. This exclusion is a result of safety restrictions that coincide with what General Strain Theory (Agnew, 2006) refers to as having a strained population. Strained individuals experience significant life stressors that pressure them to anomie. Given the prevalent absence of strained individuals from science courses, it was a pleasant surprise to learn that the Healing Outdoor Program and Education (HOPE)–a remote treatment centre in a western province in Canada–had offered a for-credit high school science program during its operation from 2005 to 2020 that was a popular pick amongst students. In order to examine the science education experiences of youth who are involved in the justice system, this case study explores the types of strains that HOPE’s students faced, how those strains affected their learning, and how the pedagogical strategies mitigated/exacerbated strains. Document analysis, interviews with teachers and staff, and a field observation revealed that a pedagogy built on relationship, place-based science education, and personalized education were integral to academic success. However, underpinning educational achievement was a distinctive holistic approach to students’ wellness that addressed their physical, mental, emotional, spiritual, and social needs, through the use of Indigenous inspired practices, other forms of therapy, and the remote wilderness location. Furthermore, this case exemplified that it is not only feasible to offer science courses to strained individuals, but also possible to use science as a catalyst to reengage strained youth with schooling when teachers have the right conditions and supports. Therefore, this study presents pedagogical approaches that were successfully used with a marginalized group and provides recommendations for HOPE as they seek out funding partners to reinstate operations, so that they can continue providing youth with hope for a better future.
32

Atomistic Simulation of Nanostructured Materials

Zhu, Ronghua (Richard) January 2006 (has links)
No description available.
33

Optical and Structural Characterization of Confined and Strained Core/Multi-Shell Semiconducting Nanowires

Fickenscher, Melodie A. 19 April 2012 (has links)
No description available.
34

Excitonic and Raman properties of ZnSe/Zn <inf>1-x</inf>Cd <inf>x</inf>Se strained-layer quantum wells

Shastri, Vasant K. January 1991 (has links)
No description available.
35

Optical properties of CdTe/Cd<sub>1-x</sub>Zn<sub>x</sub>Te strained-layer single quantum wells

Li, Tiesheng January 1993 (has links)
No description available.
36

Motivation : En kvalitativ studie om sjuksköterskors motivation under längre ansträngda situationer / Motivation : A qualitative study of nurses' motivation during longer stressful situations

Nilsson, Emma, Nilsson, Emilia, Olausson, Ella January 2021 (has links)
Purpose: The study's purpose is to test the existing motivation theories on nurses' perceptions of the phenomenon of motivation during a pandemic. Method: A cross-sectional study that deals with the phenomenon of motivation with a deductive research approach. Our data collection has taken place through a qualitative research strategy. Conclusion: The study has shown that nurses are primarily motivated by meaningfulness, appreciation and solidarity. Through the study, we have also been able to see that nurses are motivated by increased salaries and financial compensation. / Syfte: Studiens syfte är att pröva befintliga motivationsteorier på sjuksköterskors uppfattning av fenomenet motivation under en pandemi. Metod: En tvärsnittsstudie som behandlar fenomenet motivation med en deduktiv forskningsansats. Vår datainsamling har skett genom en kvalitativ forskningsstrategi. Slutsats: Studien har visat på att sjuksköterskor främst motiveras av känslan av meningsfullhet, uppskattning och gemenskap. Genom studien har vi även kunnat se att sjuksköterskor blir motiverade av ökad lön och ekonomisk ersättning.
37

Monolithic integration of functional perovskite structures on Si

Choi, Miri 19 September 2014 (has links)
Functional crystalline oxides with perovskite structure have a wide range of electrical properties such as ferroelectric, ferromagnetic, and superconductive, as well as unique properties that make them suited for a wide variety of applications including electro-optics, high-k dielectrics, and catalysis. Therefore, in order to realize the potential of perovskite oxides it is desirable to integrate them with semiconductors. Due to the high surface energy of oxides compared to that of semiconductors and the low number of oxides that are thermodynamically stable against SiO₂ formation, it has been extremely difficult to integrate epitaxial oxides with Si directly. However, in 1998, McKee and co-workers finally succeeded in depositing SrTiO₃ on Si directly using a Sr template via molecular beam epitaxy. This breakthrough opened the possibility of integrating the perovskite oxides with Si to realize potential device applications. In this dissertation, alkaline earth metal (Sr and Ba) templates on semiconductors, which enable epitaxial growth of complex oxides on semiconductors, are investigated using molecular beam epitaxy (MBE) for growth and in-situ X-ray/ultraviolet photoemission spectroscopy (XPS/UPS) for the electronic structure analysis. An epitaxial layer of SrTiO₃ on Si using such alkaline earth templates is used as a pseudo-substrate for the integration of perovskite oxides on Si. Through the use of post-deposition annealing as a function of oxygen pressure and annealing time, the strain relaxation behavior of epitaxial SrTiO₃ films grown on Si is also investigated to determine how the SiO₂ interlayer thickness affects the SrTiO₃ lattice constant. This ability to control strain relaxation can be used as a way to manipulate the properties of other perovskite oxides grown on SrTiO₃/Si. Additionally, SrTiO₃ can be made conductive by doping with La. Conductive SrTiO₃ can be used as a thermoelectric, a transparent conductive layer, and a quantum metal layer in a quantum metal field-effect transistor (QMFET). The structural, electrical, and optical properties of strained conductive La-doped SrTiO₃ are studied in order to understand the relation between elastic strain and electrical properties for electronic device applications. Oxide quantum well systems based on LaAlO₃/SrTiO₃ are also investigated using spectroscopic ellipsometry to understand how the quantum well layer structure affects the electronic structure. Such quantum well systems are good candidates for the monolithic integration of functional perovskites on semiconductors. Oxides quantum wells can be used in various device applications such as in quantum well cascade lasers, laser diodes and high performance transistors. As part of the growth optimization for high quality complex oxide heterostructures, the surface preparation of SrTiO₃ substrates using several different methods was also extensively studied using angle-resolved photoemission spectroscopy (ARPES). We found that acid-free water-based surface preparation is actually more effective at removing SrOx̳ crystallites and leaving the surface TiO₂-terminated compared to the more commonly used acid-based methods. / text
38

Measurement of Lattice Strain and Relaxation Effects in Strained Silicon Using X-ray Diffraction and Convergent Beam Electron Diffraction

Diercks, David Robert 08 1900 (has links)
The semiconductor industry has decreased silicon-based device feature sizes dramatically over the last two decades for improved performance. However, current technology has approached the limit of achievable enhancement via this method. Therefore, other techniques, including introducing stress into the silicon structure, are being used to further advance device performance. While these methods produce successful results, there is not a proven reliable method for stress and strain measurements on the nanometer scale characteristic of these devices. The ability to correlate local strain values with processing parameters and device performance would allow for more rapid improvements and better process control. In this research, x-ray diffraction and convergent beam electron diffraction have been utilized to quantify the strain behavior of simple and complex strained silicon-based systems. While the stress relaxation caused by thinning of the strained structures to electron transparency complicates these measurements, it has been quantified and shows reasonable agreement with expected values. The relaxation values have been incorporated into the strain determination from relative shifts in the higher order Laue zone lines visible in convergent beam electron diffraction patterns. The local strain values determined using three incident electron beam directions with different degrees of tilt relative to the device structure have been compared and exhibit excellent agreement.
39

Estudo do efeito de elevação atípica da transcondutância na região linear de polarização em dispositivos SOI nMOSFETS ultra-submicrométricos. / Study of gate induced floating body effect in the linear bias region in deep submicrometer nMOSFETs devices.

Agopian, Paula Ghedini Der 27 November 2008 (has links)
Este trabalho apresenta o estudo do efeito de elevação atípica da transcondutância na região linear de polarização devido ao efeito de corpo flutuante induzido pela porta (Gate Induced Floating Body Effect - GIFBE) de transistores da tecnologia SOI nMOSFET. Este estudo foi realizado com base em resultados experimentais e em simulações numéricas, as quais foram essenciais para o entendimento físico deste fenômeno. Além de contribuir com a explicação física deste fenômeno, este trabalho explora o efeito de corpo flutuante em diferentes estruturas (transistor de porta única, transistor de porta gêmea, transistor de múltiplas portas e transistores de canal tensionado), diferentes tecnologias e em função da temperatura (100K a 450K). A partir do estudo realizado em dispositivos SOI de porta única analisouse a influência das componentes da corrente de porta que tunelam através do óxido de porta do dispositivo, o potencial da região neutra do corpo do transistor, a taxa de recombinação de portadores, o impacto da redução da espessura do óxido de porta e também as dimensões físicas do transistor. Na análise feita da redução do comprimento de canal, verificou-se também que o GIFBE tende a ser menos significativo para dispositivos ultra-submicrométricos. Analisou-se também o efeito da elevação atípica da transcondutância para transistores SOI totalmente depletados, para os quais, este efeito ocorre apenas quando a segunda interface está acumulada, para as duas tecnologias estudadas (65nm e 130nm). A análise dos dispositivos de porta gêmea, que tradicionalmente são usados com a finalidade de minimizar o efeito de elevação abrupta de corrente de dreno, mostrou uma redução do GIFBE para este tipo de estrutura quando comparada à de porta única devido ao aumento da resistência série intrínseca à estrutura. O efeito de corpo flutuante também foi avaliado em função da temperatura de operação dos dispositivos. Para temperaturas variando de 100K a 450K, notou-se que o valor do limiar de GIFBE aumentou tanto para temperaturas acima de 300K quanto abaixo da mesma. Quando estes resultados são apresentados graficamente, observa-se que o comportamento do limiar de GIFBE com a temperatura resulta no formato de uma letra C, onde o valor mínimo está a 300K. Este comportamento se deve à competição entre o processo de recombinação e a degradação efetiva da mobilidade. Uma primeira análise do GIFBE em diferentes estruturas de transistores também foi realizada. Apesar dos transistores de canal tensionado apresentarem o efeito para valores menores de tensão de porta, este efeito se manifesta com menor intensidade nestes transistores, devido a alta degradação da mobilidade efetiva apresentada pelo mesmo. Entretanto, quando o foco são os transistores de múltiplas portas, os resultados obtidos demonstram que apesar destes dispositivos terem sido fabricados com dielétrico de porta de alta constante dielétrica, o GIFBE ainda ocorre. Esta ocorrência do GIFBE em FinFETs é fortemente dependente da largura do Fin, da dopagem da região de canal e conseqüentemente do acoplamento das portas laterais com a superior. / This work presents the study of the Gate Induced Floating Body Effect (GIFBE) that occurs in the SOI MOSFET technology. This study has been performed based on experimental results and on numerical simulations, which were an essential auxiliary tool to obtain a physical insight of this effect. Besides the contribution on the physical explanation of this phenomenon, in this work, the floating body effect was evaluated for different structures (single gate and twin-gate transistors), different technologies (130nm and 65nm SOI CMOS technology) and as a function of the temperature (100K to 450K). From the study of the single gate devices, it was evaluated the gate tunneling current influence on GIFBE, the body potential in the neutral region, the recombination rate, the front gate oxide thickness reduction impact, besides the physical dimensions of the transistor. In the performed analysis, taking into account the channel length reduction, it was verified that the GIFBE tends to be less important for ultra-submicron devices. The GIFBE only occurs for fully depleted devices when the second interface is accumulated. In this situation, the floating body effect influence on fully depleted devices was also studied for both technologies (65nm and 130nm). The twin-gate devices analysis, that traditionally are used in order to minimize the Kink effect, show a GIFBE reduction for this structure when it is compared to the single gate one. This enhance in the electrical characteristics is due to the series resistance increase that is intrinsic of this structures. When the temperature variation from 100K to 450K was analyzed, it was obtained the C shape behavior for the floating body effect due to a competition between the recombination process and the effective mobility degradation factor. A first evaluation of the GIFBE occurrence in new devices was also performed. When the focus is the strained silicon transistor, a occurrence of GIFBE was obtained for a lower gate voltage. Although, the GIFBE occurs earlier for strained transistor. This effect is less pronounced in this device because it presents strong effective mobility degradation. When the focus is FinFETs, the results show that although this device was fabricated with a high-k gate dielectric, the GIFBE still occurs and is strongly dependent on the device channel width.
40

SiGe-On-Insulator (SGOI) Technology and MOSFET Fabrication

Cheng, Zhiyuan, Fitzgerald, Eugene A., Antoniadis, Dimitri A. 01 1900 (has links)
In this work, we have developed two different fabrication processes for relaxed Si₁₋xGex-on-insulator (SGOI) substrates: (1) SGOI fabrication by etch-back approach, and (2) by "smart-cut" approach utilizing hydrogen implantation. Etch-back approach produces SGOI substrate with less defects in SiGe film, but the SiGe film uniformity is inferior. "Smart-cut" approach has better control on the SiGe film thickness and uniformity, and is applicable to wider Ge content range of the SiGe film. We have also fabricated strained-Si n-MOSFET’s on SGOI substrates, in which epitaxial regrowth was used to produce the surface strained Si layer on relaxed SGOI substrate, followed by large-area n-MOSFET’s fabrication on this structure. The measured electron mobility shows significant enhancement (1.7 times) over both the universal mobility and that of co-processed bulk-Si MOSFET’s. This SGOI process has a low thermal budget and thus is compatible with a wide range of Ge contents in Si₁₋xGex layer. / Singapore-MIT Alliance (SMA)

Page generated in 0.0725 seconds