CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / Increasing global energy demand has driven the development of renewable alternative energy sources, such as Dye sensitizers Solar Cells (DSSCs). In an attempt to contribute to this purpose, four new bipyridine ruthenium complexes containing substituted quinonoides ligands were synthesized and characterized for use as efficient dyes in DSSCs. The complexes were purified by using chromatographic techniques and characterized by the use of spectroscopic techniques. Experimental data obtained by UV-vis were compared with those from density functional theory (DFT) studies. The UV-vis spectra of these compounds showed bands at about 524 nm ascribed to MLCT transitions. Time-dependent DFT is in good agreement with experimental fit. The FT-IR showed the presence of characteristic bands quinonoid and bipyridine ligands. 1H NMR spectra exhibited the signals of quinonoid ligands as well as the expected correlations in each case by COSY. The mass spectra of compounds NN-bqdi-Br and NN-bqdi -COOH exhibited fragments that confirm the presence of their respective quinonoid moiety. The results show that the NN-bqdi-complex (CH3)2, NN-bqdi-COOH, Nn-bqdi-Br and NN-bqdi-(Cl)2 were obtained and with future perspectives to study the performance of these compounds such a dye for DSSCs. / O aumento da demanda energÃtica mundial tÃm impulsionado o desenvolvimento de fontes alternativas de energia renovÃveis, como as cÃlulas solares sensibilizadas por corantes (DSSCs). Na tentativa de contribuir para esse propÃsito, quatro novos complexos bipiridÃnicos de rutÃnio, contendo ligantes quinonÃides substituÃdos foram sintetizados e caracterizados para utilizaÃÃo como corantes sensibilizadores eficientes em DSSCs. Os complexos foram purificados por meio do uso de tÃcnicas cromatogrÃficas e caracterizados por meio do uso de tÃcnicas espectroscÃpicas. Os resultados de UV-vis obtidos experimentalmente foram comparados com os obtidos a partir de estudos de DFT. Os espectros de UV-vis dos compostos apresentaram bandas em aproximadamente 524 nm, atribuÃdas a transiÃÃes do tipo MLCT. A investigaÃÃo teÃrica dos complexos sintetizados neste trabalho confirma que as bandas observadas nos espectros de UV-vis dos compostos sÃo similares Ãs observadas experimentalmente, sugerindo que as bases utilizadas nos cÃlculos de DFT sÃo capazes de descrever o perfil eletrÃnico dos complexos. Os espectros vibracionais na regiÃo do infravermelho exibiram bandas caracterÃsticas da presenÃa de ligantes bipiridÃnicos e quinonÃides. Os espectros de RMN de 1H e COSY exibiram os sinais indicativos da presenÃa dos ligantes quinonÃides substituÃdos, bem como as correlaÃÃes esperadas em cada caso. Os espectros de massa dos compostos NN-bqdi-Br e NN-bqdi-COOH exibiram fragmentos que confirmam a presenÃa dos respectivos ligantes quinonÃides nestes complexos. Os resultados obtidos evidenciam que os complexos NN-bqdi-(CH3)2, NN-bqdi-COOH, NN-bqdi-Br e NN-bqdi-(Cl)2 foram obtidos e como perspectivas futuras, pretende-se estudar a performance destes compostos como corantes sensibilizadores em DSSCs.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2018-11-19T14:40:48Z No. of bitstreams: 1 wagnerdiasrocha.pdf: 3693391 bytes, checksum: ff882b197689decbd93b1281b5bf0dd5 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2018-11-23T13:04:01Z (GMT) No. of bitstreams: 1 wagnerdiasrocha.pdf: 3693391 bytes, checksum: ff882b197689decbd93b1281b5bf0dd5 (MD5) / Made available in DSpace on 2018-11-23T13:04:01Z (GMT). No. of bitstreams: 1 wagnerdiasrocha.pdf: 3693391 bytes, checksum: ff882b197689decbd93b1281b5bf0dd5 (MD5) Previous issue date: 2018-08-21 / Este trabalho apresenta uma proposta de abordagem experimental para o Efeito Fotoelétrico baseada em um kit didático capaz de demonstrar a ocorrência (ou não) do fenômeno em função da variação de intensidade e de frequência da luz incidente sobre um material receptor. O principal objetivo é fornecer uma alternativa diferenciada para a construção do conhecimento sobre o assunto. O kit, elaborado com LEDs e outros componentes de baixo custo presentes no cotidiano, é de fácil reprodução e operação, além de compacto o suficiente para viabilizar a execução de atividades práticas em qualquer sala de aula, sendo assim muito útil principalmente para alunos e professores do Ensino Médio, os quais muitas vezes não dispõem de laboratórios e equipamentos, seja pela restrição de acesso ou até mesmo pela inexistência destes. Com três aplicações em sala de aula, desenvolveu-se uma metodologia onde duas hipóteses excludentes entre si e que se apresentam como explicação para o fenômeno são confrontadas experimentalmente. A validade de somente uma dessas hipóteses é comprovada pelas respostas dadas a dois questionamentos pós-atividade. Os resultados obtidos demonstram que os alunos conseguiram compreender o funcionamento do kit, utilizá-lo para realizar a atividade proposta e construir eles próprios o seu conhecimento sobre o assunto. Além disso, as críticas e sugestões coletadas ao final do processo demonstram que houve uma aceitação considerável da proposta pelos mesmos. A fim de torná-la acessível aos professores de Física interessados na sua utilização, são fornecidos adicionalmente dois roteiros, sendo que um descreve passo a passo a montagem do kit e o outro dá suporte à execução da atividade experimental proposta. / This work presents a proposal for an experimental approach to the Photoelectric Effect based on a didactic kit capable of demonstrating the occurrence (or not) of the phenomenon as a function of the variation of intensity and frequency of light incident on a receiving material. The main objective is to provide a differentiated alternative for building knowledge about the subject. The kit, made with LEDs and other low-cost components present in everyday life, is easy to reproduce and operate, and compact enough to enable the execution of practical activities in any classroom, and is therefore very useful mainly for students and teachers of secondary education, which often do not have laboratories and equipment, either by the restriction of access or even by the lack of them. With three applications in the classroom, a methodology was developed where two mutually exclusive hypotheses that present themselves as an explanation for the phenomenon are confronted experimentally. The validity of only one of these hypotheses is proven by the responses given to two post-activity questions. The obtained results demonstrate that the students were able to understand the operation of the kit, use it to carry out the proposed activity and build their own knowledge about the subject. In addition, the criticisms and suggestions collected at the end of the process demonstrate that there has been considerable acceptance of the proposal by the parties. In order to make it accessible to physics teachers interested in its use, two scripts are additionally provided, one describing step by step the assembly of the kit and the other supporting the execution of the proposed experimental activity.

The aim of the diploma work is to introduce analytical methods concerning solar panels and systems. Firstly, the attention is drawn to a principle of photovoltaic conversion including an explanation of photoelectric phenomenon as well as the issue of P-N junction considered to be the fundamental building block of a solar cell. With respect to the fact that the diploma work is to be focused on testing of solar panels and the identification of defects in solar cells, the work describes individual solar cells, solar panels as well as individual methods of defect identification. Secondly, the work includes sections dealing with the assessment of the measurement performed by using electroluminescence method as well as the measurement method of volt-ampere parameters. The last section of the work includes the assessment of solar panel aging after one-year performance using the electroluminescence measurement method.

Electronic photoelectric barriers are established devices to time subjects in experiments or athletes in sports. The systems are reliable and precise, but also expensive. We propose a novel, affordable photoelectric barrier system based on consumer grade camera hardware and show how to build such a system with common electronic components and a smartphone. In two experiments with track and field athletes, we show that our novel system has similar accuracy than a professional photoelectric barrier system, but for a fraction of the costs.:1. Introduction 1.1 Motivation 1.2 Commercial Photoelectric Barriers 1.3 Image-based Change Detection 1.4 Existing Camera-based Systems 2. Novel Photoelectric Virtual Barriers System 2.1 Virtual Image-based Photoelectric Barriers 2.2 Mobile Image-based Photoelectric Virtual Barrier System 3. Experiments 4. Conclusion & Future Work

L’innovation pédagogique pour elle-même s’avère parfois discutable, mais elle se justifie quand les enseignants se heurtent aux difficultés d’apprentissage de leurs étudiants. En particulier, certaines notions de physique sont réputées difficiles à appréhender par les étudiants, comme c’est le cas pour l’effet photoélectrique qui n’est pas souvent compris par les étudiants au niveau collégial. Cette recherche tente de déterminer si, dans le cadre d’un cours de physique, la simulation de l’effet photoélectrique et l’utilisation des dispositifs mobiles et en situation de collaboration favorisent une évolution des conceptions des étudiants au sujet de la lumière. Nous avons ainsi procédé à l’élaboration d’un scénario d’apprentissage collaboratif intégrant une simulation de l’effet photoélectrique sur un ordinateur de poche. La conception du scénario a d’abord été influencée par notre vision socioconstructiviste de l’apprentissage. Nous avons effectué deux études préliminaires afin de compléter notre scénario d’apprentissage et valider la plateforme MobileSim et l’interface du simulateur, que nous avons utilisées dans notre expérimentation : la première avec des ordinateurs de bureau et la seconde avec des ordinateurs de poche. Nous avons fait suivre à deux groupes d’étudiants deux cours différents, l’un portant sur une approche traditionnelle d’enseignement, l’autre basé sur le scénario d’apprentissage collaboratif élaboré. Nous leur avons fait passer un test évaluant l’évolution conceptuelle sur la nature de la lumière et sur le phénomène de l’effet photoélectrique et concepts connexes, à deux reprises : la première avant que les étudiants ne s’investissent dans le cours et la seconde après la réalisation des expérimentations. Nos résultats aux prétest et post-test sont complétés par des entrevues individuelles semi-dirigées avec tous les étudiants, par des enregistrements vidéo et par des traces récupérées des fichiers logs ou sur papier. Les étudiants du groupe expérimental ont obtenu de très bons résultats au post-test par rapport à ceux du groupe contrôle. Nous avons enregistré un gain moyen d’apprentissage qualifié de niveau modéré selon Hake (1998). Les résultats des entrevues ont permis de repérer quelques difficultés conceptuelles d’apprentissage chez les étudiants. L’analyse des données recueillies des enregistrements des séquences vidéo, des questionnaires et des traces récupérées nous a permis de mieux comprendre le processus d’apprentissage collaboratif et nous a dévoilé que le nombre et la durée des interactions entre les étudiants sont fortement corrélés avec le gain d’apprentissage. Ce projet de recherche est d’abord une réussite sur le plan de la conception d’un scénario d’apprentissage relatif à un phénomène aussi complexe que l’effet photoélectrique, tout en respectant de nombreux critères (collaboration, simulation, dispositifs mobiles) qui nous paraissaient extrêmement utopiques de réunir dans une situation d’apprentissage en classe. Ce scénario pourra être adapté pour l’apprentissage d’autres notions de la physique et pourra être considéré pour la conception des environnements collaboratifs d’apprentissage mobile innovants, centrés sur les besoins des apprenants et intégrant les technologies au bon moment et pour la bonne activité. / The educational innovation itself is sometimes debatable but it is justified when the teachers confront the learning difficulties of their students. In particular, some notions of physics are notoriously hard for students to understand, as is the case for the photoelectric effect which is not often comprehended by the students at the college level. This research tries to determine if, as part of a physics course, the simulation of the photoelectric effect and the use of mobile devices in collaborative situations facilitate an evolution of the student’s conceptions about the concept of light. We have proceeded to develop a scenario of collaborative learning by integrating a simulation of the photoelectric effect on handheld devices (Pocket PC). The design of scenario was first influenced by our socioconstructivist vision of learning. We conducted two preliminary studies to complete our scenario of learning and to validate the platform « MobileSim » and the interface of the simulator used in our experiment. The first studies were completed with a simulation on computers and the second with a simulation on Pocket PC. After that, we carried out the experimentation with two groups of students. The control group was assigned to the traditional approach of teaching and the experimental group was assigned to the approach based on the developed scenario of collaborative learning. We have conducted a test twice to assess a conceptual change about the nature of light and about the phenomenon of the photoelectric effect and related concepts. The first test (pre-test) before the students are involved in the course and the second (post-test) after completion of experiments. Our results in the pre-test and post-test were completed by conducting semi-structured individual interviews with all students, by video recordings and recovered traces (on log files or on paper). Students in the experimental group obtained good results in the test compared to those of the control group. We noted an average gain of learning qualified at a moderate level according to Hake (1998). Interview results were used to identify some conceptual difficulties of student learning. Analysis of collected data from video sequences, questionnaires and recovered tracks allowed us to better understand the process of collaborative learning and has revealed that the number and the time of interactions between students are strongly correlated with the gain of learning. At first, this research project is a success in the designing of a learning scenario of a phenomenon as complex as the photoelectric effect and respects many criteria (collaboration, simulation, mobile devices, etc.) that it seemed for us extremely utopian to combine them in an effective learning situation in the classroom. For instance, this scenario could be adapted to the learning of other concepts in physics. It could also be considered for the design of collaborative environments for innovative mobile learning focused on the needs of learners that integrate the technologies at the right time and for the right activity.

Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2018-01-22T23:42:19Z No. of bitstreams: 1 Dissertacao-Alexandre-com Ficha catalografica.pdf: 2537452 bytes, checksum: ef66f70b176f6db12dc9aba025173ff1 (MD5) / Made available in DSpace on 2018-01-22T23:42:19Z (GMT). No. of bitstreams: 1 Dissertacao-Alexandre-com Ficha catalografica.pdf: 2537452 bytes, checksum: ef66f70b176f6db12dc9aba025173ff1 (MD5) Previous issue date: 2016-08-05 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Teaching-learning physics processis a challenge in Brazil and the world. Currently, there is a consensus of the existence of a great difficulty in teaching physics at all levels of education. Teachers complain mainly of disinterest, lack of student motivation to learn physics, besides the widespread practice of finding schoolsteaching physicsby teachers who do not have a degree in physics, the number of physics teacher are insufficient and the quality of their formation often are questioned. These factors undoubtedly have hindered the ways to bring the physics contents to the classroom, and especially those related to modern and contemporary physics. The photoelectric effect is a phenomenon of modern physics and we can see it, in the day to day functioning of the doors of malls, in public lighting system, alarm systems, among others. In this work an educational software for PC or learning object, in form of a game about the photoelectric effect was developed in Java programming language. The main objective was to motivate the student to learn some concepts of contemporary physics, and thus provide a significant learning basics of the photoelectric effect, according to Ausubel's theory. The learning object consists of a data-sheet explain the stages of the game, some evaluation questions, which should be learned the basics of the photoelectric effect. Before and after using the software by student?s questionnaires were applied to assess the level of learning these concepts and motivation for learning science. A teaching and learning strategy using the LO was applied to a class of ninth year of elementary school in a public school from the city of Lauro de Freitas, Bahia. From the analysis of the results we can say that the application of LO in students of elementary school, generated a certain level of learning of the subjects on the photoelectric effect. At the same time, it was observed an increase in average student motivation index. The Cronbach's alpha was 0.86, showing a high value of reliability of data from the questionnaires. We highlight that the application of educational product, the proposed learning strategy, proved valid and suggest its use for teaching and motivation of elementary school students in learning some concepts of Contemporary Physics and Modern, through the photoelectric effect. / O processo de ensino-aprendizagem de f?sica ? um desafio da educa??o no Brasil e no Mundo. Atualmente, h? um consenso de que existe uma grande dificuldade em ensinar f?sica em todos os n?veis de ensino. Os professores queixam-se principalmente do desinteresse acompanhado da falta de motiva??o dos alunos em querer aprender f?sica, al?m da pr?tica generalizada de encontrar nas escolas, professores n?o graduados em f?sica leccionando f?sica, e os que existem s?o em n?mero insuficiente e a qualidade de sua forma??o muitas vezes questionada. Estes fatores sem d?vidas t?m dificultado as formas de levar o conte?do de f?sica e principalmente os relacionados com os conte?dos da f?sica moderna e contempor?nea para sala de aula. O efeito fotoel?trico ? um fen?meno da f?sica moderna e contempor?nea e podemos observa-lo no dia a dia no funcionamento das portas de shoppings, no sistema de ilumina??o p?blica, em sistemas de alarme, dentre outros. Neste trabalho foi desenvolvido um software educacional ou objeto de aprendizagem para PC, em forma de jogo sobre o efeito fotoel?trico, desenvolvido na linguagem de programa??o Java. O objetivo maior foi o de motivar o aluno ao aprendizado de alguns conceitos da f?sica moderna e contempor?nea, e assim, proporcionar uma aprendizagem significativa de conceitos b?sicos do efeito fotoel?trico, de acordo com a teoria de Ausubel. O objeto de aprendizagem ? formado por uma apostila, um question?rio e um jogo com v?rias fases, onde dever?o ser aprendidos os conceitos b?sicos do efeito fotoel?trico. Antes e ap?s o uso do software pelos estudantes foram aplicados question?rios para avaliar o n?vel de aprendizagem desses conceitos e a motiva??o ao aprendizado de ci?ncias. Foi criada uma estrat?gia de ensino-aprendizagem usando o OA e aplicada numa turma do nono ano do ensino fundamental em uma escola p?blica, no munic?pio de Lauro de Freitas, Bahia. Das an?lises dos resultados obtidos podemos afirmar que a aplica??o do OA nos estudantes do 9 ano do ensino fundamental, gerou um certo n?vel de aprendizagem dos assuntos abordados sobre o efeito fotoel?trico. Ao mesmo tempo foi constatado um aumento na m?dia do ?ndice de motiva??o dos estudantes. O coeficiente alfa de Cronbach foi de 0.86, mostrando um valor elevado de confiabilidade dos dados dos question?rios aplicados. Podemos destacar que a aplica??o do produto did?tico, com a estrat?gia de aprendizagem proposta, mostrou-se v?lido e sugerimos sua utiliza??o, para o ensino e motiva??o dos alunos do ensino fundamental no aprendizado de alguns conceitos da F?sica Contempor?nea e Moderna, atrav?s do efeito fotoel?trico.

Submitted by Larissa Vitoria Cardoso Cusielo (larissavitoria@id.uff.br) on 2017-09-04T20:04:17Z No. of bitstreams: 4 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Ricardo Monteiro da Silva - Dissertação Final.pdf: 3758859 bytes, checksum: 49af3504c4aab0f5b413eb6a8e306b18 (MD5) Ricardo Monteiro da Silva - Produto Final.pdf: 1135898 bytes, checksum: f780e3a33731edd0ccaaf7abee1165a9 (MD5) Ricardo Monteiro da Silva - Manual de Aplicacao Final.pdf: 512795 bytes, checksum: 076a5132843eca4ea0c8e8eeca05ae29 (MD5) / Approved for entry into archive by Biblioteca do Aterrado BAVR (bavr@ndc.uff.br) on 2017-09-05T19:21:50Z (GMT) No. of bitstreams: 4 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Ricardo Monteiro da Silva - Dissertação Final.pdf: 3758859 bytes, checksum: 49af3504c4aab0f5b413eb6a8e306b18 (MD5) Ricardo Monteiro da Silva - Produto Final.pdf: 1135898 bytes, checksum: f780e3a33731edd0ccaaf7abee1165a9 (MD5) Ricardo Monteiro da Silva - Manual de Aplicacao Final.pdf: 512795 bytes, checksum: 076a5132843eca4ea0c8e8eeca05ae29 (MD5) / Made available in DSpace on 2017-09-05T19:21:50Z (GMT). No. of bitstreams: 4 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Ricardo Monteiro da Silva - Dissertação Final.pdf: 3758859 bytes, checksum: 49af3504c4aab0f5b413eb6a8e306b18 (MD5) Ricardo Monteiro da Silva - Produto Final.pdf: 1135898 bytes, checksum: f780e3a33731edd0ccaaf7abee1165a9 (MD5) Ricardo Monteiro da Silva - Manual de Aplicacao Final.pdf: 512795 bytes, checksum: 076a5132843eca4ea0c8e8eeca05ae29 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Universidade Federal Fluminense. Instituto de Ciências Exatas. Programa de Pós-Graduação em Ensino de Física. Volta Redonda, RJ. / A introdução de tópicos de física moderna no ensino médio já é uma realidade em praticamente todo país. No Estado do Rio de Janeiro, onde temos a adoção de um currículo mínimo, percebemos que esta introdução se dá de forma a privilegiar uma discussão conceitual, levando o aluno a refletir o mundo a sua volta e as tecnologias que estão presentes cada vez mais na sociedade. Muitas destas tecnologias são apoiadas em conceitos que envolvem conceitos de mecânica quântica, entre outros temas de física contemporânea. O uso de tecnologia de informação pelos alunos com seus “telefones inteligentes” abre espaço para introduzir ferramentas de tecnologia de informação no ensino de física, sobretudo o uso de simulações. Nesta dissertação apresentamos a elaboração de um produto educacional voltado ao ensino do efeito fotoelétrico no ensino médio através do uso do simulador PHET. O produto desenvolvido é uma sequência didática com questionários de levantamento de conhecimento prévio, leitura de material instrucional, pesquisa bibliográfica e realização de simulação, seguindo um roteiro de perguntas. Uma breve discussão sobre as bases teóricas que suportaram o desenvolvimento do produto é apresentada, bem como a metodologia empregada para a confecção do produto proposto. Descrevemos a aplicação do produto, bem como apresentamos uma avaliação do mesmo com a técnica de análise de conteúdo para as respostas dadas aos questionários e roteiros. O produto foi aplicado com sucesso e podemos inferir que sua utilização é viável, podendo ser uma boa opção para o ensino do efeito fotoelétrico. / The introduction of modern physics topics in secondary education is already a reality in virtually all over the country. In the state of Rio de Janeiro, where we have to adopt a minimum curriculum, we realize that this introduction is given in order to favor a conceptual discussion, leading students to reflect the world around them and the technologies that are increasingly present in our society. Many of these technologies are supported by concepts involving quantum mechanical concepts among other contemporary physics topics. The use of information technology by students with their "smartphones" makes room for introducing information technology tools in physics education, especially the use of simulations. In this thesis we present the design of an educational product geared to teaching the photoelectric effect in high school through the use of PHET simulator. The product developed is a didactic sequence with prior knowledge of survey questionnaires, reading instructional materials and literature, and conducting simulation following a script of questions. A brief discussion of the theoretical foundations that have supported the development of the product is presented and the methodology used for the preparation of the proposed product. We describe the application of the product and present an evaluation of it with the content analysis technique to the responses to the questionnaires and scripts. The product has been successfully applied and we can infer that their use is feasible, and it also can be a good option for teaching the photoelectric effect.

Ce travail de thèse porte sur la conception et la réalisation de méta-structures pour l’amelioration des performances de détecteurs dans les gammes spectrales du moyen infrarouge et du térahertz (THz). Ces méta-structures sont des matrices de résonateurs métalliques qui actent aussi comme antennes, permettant une meilleure collection des photons et un plus fort confinement du champ électrique. Dans ce manuscrit, j’examine les résultats expérimentaux concernant deux photo-detecteurs infrarouges à puits quantiques (QWIP) résonants à une longueur d'onde de 55.5 µm (5.4 THz) et de 8.6 µm, implémentés dans des réseaux d’antennes patch. La responsivité, la détectivité et les performances thermiques des dispositifs en microcavité sont systématiquement comparées au même détecteur fabriqué en géométrie standard ‘mesa’, pour lequel le rayonnement infrarouge est couplé par le substrat. La cohérence du modèle est évaluée en comparant le gain photoconducteur de chaque structure QWIP. Dans le moyen infrarouge, le fonctionnement à température ambiante avec une source de radiation thermique est démontré pour la première fois. De plus, en exploitant la courte durée de vie des porteurs dans la zone de QWIP, une détection hétérodyne à température ambiante a été démontrée jusqu’aux fréquences de quelques GHz, limitée uniquement par la fréquence de coupure du circuit externe. Dans la dernière partie de ce manuscrit, plusieurs perspectives sont discutées concernant des structures de détecteurs quantiques couplés à la géométrie de résonateurs patch et des architectures inspirées des métamateriaux, avec la perspective d’améliorer davantage les performances des photodétécteurs / The present thesis manuscript is about the conception and the realisation of metastructures for the improvement of detector performances in the mid-infrared and terahertz (THz) spectral ranges. These meta-structures are arrays of metal resonators that also act as antennas, allowing a better collection of photons and a stronger confinement of the electric field. In this manuscript, I examine the experimental results regarding a 55.5 µm (5.4 THz) and a 8.6 µm quantum well infrared photodetectors (QWIP), implemented into patch-antennae arrays. The responsivity, the specific detectivity and the thermal performances of the antenna-coupled devices are systematically compared to the same detector processed in standard substrate-coupled ‘mesa’ geometry. In the mid-infrared, the room temperature operation using a thermal radiation source is reported for the first time. Moreover, exploiting the short carrier lifetime in semiconductor quantum wells, a room temperature heterodyne detection is demonstrated, at frequencies up to few GHz, limited only by the cut-off frequency of the external circuit. In the last part of this work, several perspectives are discussed, regarding alternative quantum detector structures coupled to the patch resonators geometry and innovative circuit-like plasmonic architectures, envisioning orders of magnitude improvement in photodetector performances

L’innovation pédagogique pour elle-même s’avère parfois discutable, mais elle se justifie quand les enseignants se heurtent aux difficultés d’apprentissage de leurs étudiants. En particulier, certaines notions de physique sont réputées difficiles à appréhender par les étudiants, comme c’est le cas pour l’effet photoélectrique qui n’est pas souvent compris par les étudiants au niveau collégial. Cette recherche tente de déterminer si, dans le cadre d’un cours de physique, la simulation de l’effet photoélectrique et l’utilisation des dispositifs mobiles et en situation de collaboration favorisent une évolution des conceptions des étudiants au sujet de la lumière. Nous avons ainsi procédé à l’élaboration d’un scénario d’apprentissage collaboratif intégrant une simulation de l’effet photoélectrique sur un ordinateur de poche. La conception du scénario a d’abord été influencée par notre vision socioconstructiviste de l’apprentissage. Nous avons effectué deux études préliminaires afin de compléter notre scénario d’apprentissage et valider la plateforme MobileSim et l’interface du simulateur, que nous avons utilisées dans notre expérimentation : la première avec des ordinateurs de bureau et la seconde avec des ordinateurs de poche. Nous avons fait suivre à deux groupes d’étudiants deux cours différents, l’un portant sur une approche traditionnelle d’enseignement, l’autre basé sur le scénario d’apprentissage collaboratif élaboré. Nous leur avons fait passer un test évaluant l’évolution conceptuelle sur la nature de la lumière et sur le phénomène de l’effet photoélectrique et concepts connexes, à deux reprises : la première avant que les étudiants ne s’investissent dans le cours et la seconde après la réalisation des expérimentations. Nos résultats aux prétest et post-test sont complétés par des entrevues individuelles semi-dirigées avec tous les étudiants, par des enregistrements vidéo et par des traces récupérées des fichiers logs ou sur papier. Les étudiants du groupe expérimental ont obtenu de très bons résultats au post-test par rapport à ceux du groupe contrôle. Nous avons enregistré un gain moyen d’apprentissage qualifié de niveau modéré selon Hake (1998). Les résultats des entrevues ont permis de repérer quelques difficultés conceptuelles d’apprentissage chez les étudiants. L’analyse des données recueillies des enregistrements des séquences vidéo, des questionnaires et des traces récupérées nous a permis de mieux comprendre le processus d’apprentissage collaboratif et nous a dévoilé que le nombre et la durée des interactions entre les étudiants sont fortement corrélés avec le gain d’apprentissage. Ce projet de recherche est d’abord une réussite sur le plan de la conception d’un scénario d’apprentissage relatif à un phénomène aussi complexe que l’effet photoélectrique, tout en respectant de nombreux critères (collaboration, simulation, dispositifs mobiles) qui nous paraissaient extrêmement utopiques de réunir dans une situation d’apprentissage en classe. Ce scénario pourra être adapté pour l’apprentissage d’autres notions de la physique et pourra être considéré pour la conception des environnements collaboratifs d’apprentissage mobile innovants, centrés sur les besoins des apprenants et intégrant les technologies au bon moment et pour la bonne activité. / The educational innovation itself is sometimes debatable but it is justified when the teachers confront the learning difficulties of their students. In particular, some notions of physics are notoriously hard for students to understand, as is the case for the photoelectric effect which is not often comprehended by the students at the college level. This research tries to determine if, as part of a physics course, the simulation of the photoelectric effect and the use of mobile devices in collaborative situations facilitate an evolution of the student’s conceptions about the concept of light. We have proceeded to develop a scenario of collaborative learning by integrating a simulation of the photoelectric effect on handheld devices (Pocket PC). The design of scenario was first influenced by our socioconstructivist vision of learning. We conducted two preliminary studies to complete our scenario of learning and to validate the platform « MobileSim » and the interface of the simulator used in our experiment. The first studies were completed with a simulation on computers and the second with a simulation on Pocket PC. After that, we carried out the experimentation with two groups of students. The control group was assigned to the traditional approach of teaching and the experimental group was assigned to the approach based on the developed scenario of collaborative learning. We have conducted a test twice to assess a conceptual change about the nature of light and about the phenomenon of the photoelectric effect and related concepts. The first test (pre-test) before the students are involved in the course and the second (post-test) after completion of experiments. Our results in the pre-test and post-test were completed by conducting semi-structured individual interviews with all students, by video recordings and recovered traces (on log files or on paper). Students in the experimental group obtained good results in the test compared to those of the control group. We noted an average gain of learning qualified at a moderate level according to Hake (1998). Interview results were used to identify some conceptual difficulties of student learning. Analysis of collected data from video sequences, questionnaires and recovered tracks allowed us to better understand the process of collaborative learning and has revealed that the number and the time of interactions between students are strongly correlated with the gain of learning. At first, this research project is a success in the designing of a learning scenario of a phenomenon as complex as the photoelectric effect and respects many criteria (collaboration, simulation, mobile devices, etc.) that it seemed for us extremely utopian to combine them in an effective learning situation in the classroom. For instance, this scenario could be adapted to the learning of other concepts in physics. It could also be considered for the design of collaborative environments for innovative mobile learning focused on the needs of learners that integrate the technologies at the right time and for the right activity.

Made available in DSpace on 2015-09-25T12:19:38Z (GMT). No. of bitstreams: 1 Valdenes Carvalho Gomes 1.pdf: 1865156 bytes, checksum: d95cdb9f00d22cd9d1f0643654acc86b (MD5) Previous issue date: 2011-10-14 / Studies showed that the use of information and communication technologies contributes to the educational practice in any level of education. However, it requires changes on the teacher s working methods, generat ing changes on the operation of the institutions and on the educational system. An information and communication technology must involve some kind of material object, which is part of the educational praxis related to the teaching process with some kind of relationship between the teacher-technology and technology-student. In our work we aim to investigate how a computer simulation can help the teaching of acontent of modern physics in high. A computational simulation is an activity that allows the student to manipulate and observe situations that mimic or approximate to a real physical phenomenon. The didactic intervention was performed in four consecutive meetings, each with one hundred minutes long. For this production and performance, we made use of a didactic text, a guide for the activity performance with the computational simulator, an evaluation questionnaire and a learning check activity. The results revealed that the students classified the computational simulation as a good way to approach the subject. Therefore, the use of computational simulations can provide an attractive teaching perspective, however it must be performed in a compatible way to the adopted teaching methodology. / Estudos demonstram que a utilização das tecnologias de informação e comunicação contribui para a prática educativa em qualquer nível de ensino. No entanto, ela impõe mudanças nos métodos de trabalho dos professores, gerando modificações no funcionamento das instituições e no sistema educativo. Uma tecnologia de informação e comunicação educacional deve envolver algum tipo de objeto material, que faça parte da práxis educativa relativa ao processo de ensino com algum tipo de relação entre o professortecnologia e tecnologia-estudante. No nosso trabalho objetivamos investigar como uma simulação computacional pode ajudar o ensino de um conteúdo de física moderna e contemporânea no ensino médio. Uma simulação computacional é uma atividade que permite o estudante manipular e observar situações que imitam ou se aproximam de um fenômeno físico real. A intervenção didática foi realizada em quatro encontros consecutivos cada um com cem minutos de duração. Para a produção e execução dessa intervenção fizemos o uso de um texto didático, de um roteiro para realização da atividade com o simulador computacional, de um questionário de avaliação e de uma atividade de verificação de aprendizagem. Os resultados revelaram que os estudantes classificaram a simulação computacional como uma boa forma de expor o conteúdo. Assim, a utilização de simulações computacionais pode se constituir numa perspectiva de um ensino atraente, entretanto, deve ser feita de forma compatível com a metodologia de ensino a ser empregada.