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A quantitative method for extracting minority carrier diffusion and drift lengths is developed and demonstrated in a heavily-doped semiconductor heterostructure. This method advances the high resolution transport imaging technique, yielding key material parameters with a single, non-destructive measurement. This is the first demonstration of an SEM-based, contact-free, non-destructive technique for high-resolution minority carrier lifetime measurement. The measured values are in excellent agreement with theoretical calculations. The imaging transport technique is also employed to image the nature of the generation region as a function of beam energy, probe current and sample atomic number. These types of images should be useful to allow for experimental verification of resolution limits in CL and EBIC associated with interaction volume effects in bulk materials and can be obtained without additional sample preparation. Finally, several suggestions for further research are offered, including mapping of radiation damage in solar cells, near-contact E field mapping and studies of low-dimensional structures such as superlattices and quantum wires. These nanoscale structures are poised to usher-in the next revolution in solid-state electronic devices.

Law Chi Tat = 砷銻化鎵量子井的表面形態及發光的研究 / 羅志達. / On t.p. "x" is subscript. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 91-92). / Text in English; abstracts in English and Chinese. / Law Chi Tat = shen ti hua jia liang zi jing de biao mian xing tai ji fa guang de yan jiu / Luo Chida. / ACKNOWLEDGMENTS --- p.i / ABSTRACT --- p.ii / TABLE OF CONTENTS --- p.iv / LIST OF TABLES --- p.vi / LIST OF FIGURES --- p.vii / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 1.1 --- Motivations --- p.1 / Chapter 1.2 --- Principle of CL --- p.2 / Chapter 1.3 --- Possible Mechanisms Leading to Luminescence Variation --- p.5 / Chapter 1.4 --- Subjects to be Studied Experimentally --- p.11 / Chapter 2. --- EXPERIMENTAL CONDITIONS AND PROCEDURES --- p.12 / Chapter 2.1 --- Samples --- p.12 / Chapter 2.2 --- Morphological Studies of Surface --- p.12 / Chapter 2.3 --- Luminescence Studies --- p.13 / Chapter 2.3.1 --- RT CL Studies --- p.13 / Chapter 2.3.1.1 --- SEM Settings --- p.13 / Chapter 2.3.1.2 --- CL Settings --- p.14 / Chapter 2.3.1.3 --- Phase Sensitive Detection Part --- p.15 / Chapter 2.3.1.4 --- Data Acquisitions --- p.15 / Chapter 2.3.2 --- LT CL Studies at 74 K --- p.15 / Chapter 2.3.2.1 --- Calibration of the Primary Beam Current at 74 K --- p.16 / Chapter 2.3.3 --- Special Precautions during Acquisition of CL Data --- p.16 / Chapter 2.3.4 --- Auxiliary Experiments --- p.18 / Chapter 3. --- EXPERIMENTAL RESULTS --- p.19 / Chapter 3.1 --- Results on Surface Morphology --- p.19 / Chapter 3.2 --- Results on Luminescence Property --- p.21 / Chapter 3.2.1 --- CL Images --- p.21 / Chapter 3.2.2 --- Kinetic Curves of CL from GaAs1-xSbx --- p.23 / Chapter 3.2.3 --- Kinetic Curves of CL from Substrate --- p.30 / Chapter 3.2.4 --- CL Spectra --- p.30 / Chapter 3.2.5 --- Effects of Different Electron Beam Accelerating Voltages --- p.44 / Chapter 3.2.6 --- Results on Temperature Dependence --- p.44 / Chapter 3.2.7 --- Results on Auxiliary Experiments --- p.57 / Chapter 4. --- DATA ANALYSIS AND DISCUSSION --- p.63 / Chapter 4.1 --- Dose Effect --- p.63 / Chapter 4.1.1 --- Electron Dose Dependence of Kinetic Curve --- p.63 / Chapter 4.1.2 --- Empirical Fitting of Dose Curve --- p.66 / Chapter 4.1.3 --- Dose Curves Obtained at 74 K --- p.72 / Chapter 4.1.4 --- Conversion of Dose Effect to Energy Effect --- p.73 / Chapter 4.2 --- Discussion on Possible Mechanisms Leading to Luminescence Variation According to Literature --- p.78 / Chapter 4.3 --- The Surface Roughness at DifferentX --- p.88 / Chapter 5. --- CONCLUSIONS --- p.90 / REFERENCES --- p.91

The rational design of ligand architectures that enables the development of well-defined metallic constructs has long been recognized as an avenue toward controlling and/or tuning the properties of the corresponding material. To date, one of the most widely studied ligand systems is 2,2’;6’,2”-terpyridine, whose tridentate chelating environment allows for coordination to a variety of metal ions with a wide range of geometries. The development of a terpy-like framework which incorporates a boratriazine moiety into the central ring has been recently reported by the Brusso group, namely 2,2-difluoro-4,6-bis(2-pyridyl)-1,3-dihydro-1,3,5,2-triazaborinine (Py2F2BTA) and 2,2-difluoro-4,6-bis(2-4,6-pyrimidinyl)-1,3-dihydro-1,3,5,2-triazaborinine (Pm2F2BTA). These compounds constitute unfused analogues to the extensively studied boron dipyrromethene (bodipy) family of luminophores, which are known for their high thermal resistance, chemical robustness, low photodegradation, and interesting photophysical signatures. While numerous bodipy derivatives have been studied, metal coordination with these compounds remains an intricate property to explore. Thus, the work presented herein represents the first investigations into the coordination chemistry of these novel ligand frameworks. Chapter one serves as an introduction to coordination chemistry, exploring important concepts as they relate to the field; the origin of our boratriazine based ligands is also explored within this chapter. Chapter two aims to describe trends in coordination and reactivity of these ligands with iron and cobalt metal sources of different oxidation states. The third and fourth chapter focuses on the targeted use of azide and thiocyanate ligands, respectively, to promote interesting magnetic interactions in related complexes. In the fifth chapter, luminescent metal complexes synthesized through the use of d10 metals are described. Conclusions and future outlooks are then presented in the final section, chapter six.

O germe desta tese data de mais de quinze anos quando, em conexão com outro trabalho, correlato se bem que bastante voltado para a tecnologia [TRZE85a] , um artigo [SCHA71a] chamou a atenção para os fatos de que (i) a ausência de recaptura na luminescência termicamente ativada implicava um mecanismo de cinética de primeira ordem; (ii) nestas condições, ter-se-ia uma densidade eletrônica monotonicamente crescente no nível para os quais os elétrons (buracos) eram libertados; (iii) sendo tal nível a banda de condução (valência), seria detectável uma condutividade elétrica permanente, contrariamente a todas as observações experimentais (sem falar que a explicação para a transitoriedade da própria luminescência se tomaria complicada). Ora, se tal era a situação, por que se insistia tanto em buscar ajustes numéricos de parâmetros de armadilhas e de modelos de processos, questionando a ordem de cinética (cujo conhecimento é indispensável para que os valores encontrados façam sentido, [BRAU79b]), em lugar de primeiro se obterem experimentalmente as informações necessárias? Urgia fazê-lo, era premente a disponibilidade de um equipamento experimental que o permitisse. Esta perspectiva conduziu ao desenvolvimento do SEX-Sistema Experimental Multi-propósito no Domínio Eletroóptico, descrito detalhadamente no sexto capítulo. Resumidamente, trata-se de um dispositivo integrado de medição, capaz de operar na faixa de 80 K até 800 K sob vácuo ou outra atmosfera escolhida qualquer, com o qual se podem realizar experimentos de radio-, termo-, foto- e eletroluminescência, radio-, termo- e fotocorrentes elétricas (com e sem campo elétrico externo aplicado) e, ainda, perdas dielétricas; é possível igualmente nele se efetuarem tratamentos de amostras,explorando as modalidades de transferência de energia envolvidas nas técnicas de detecção acima citadas. No sétimo capítulo, estão mostrados alguns resultados obtidos com o equipamento no estágio de desenvolvimento em que ele presentemente se encontra. Das cerca de setenta partes e peças que o constituem, 70% foram especialmente projetadas e executadas. A preocupação, desencadeada pelo trabalho de Scharmann a que se aludiu acima, não se limitou, porém, a somente propiciar a disponibilidade de novos recursos para o laboratório. Ela gerou diretrizes e posturas comprometidas com a otimização das ações envolvidas no trabalho experimental, visando a maximizar a relação entre as informações obtidas e o esforço dispendido. Aplicar uma dada técnica à investigação de uma amostra corresponde a fazer uma pergunta à natureza: a proposta dos quatro Princípios descritos no segundo capítulo é indicar qual a melhor pergunta a ser feita em cada momento da investigação; complementarmente, os capítulos terceiro e quarto envolvem partes importantes do conhecimento exigido para que as respostas obtidas sejam entendidas e interpretadas adequadamente. Pode parecer curioso que, embora o capítulo quinto não seja o último deste trabalho, a descrição de seu conteúdo venha a ser feita somente no parágrafo final deste resumo. Há uma razão determinante para que assim seja: o que lá se aborda não são resultados do SEX mas, sim e ao mesmo tempo, pais e filhos da filosofia, dos Principias para o Estudo de Defeitos em Materiais no Domínio Eletroóptico. Os resultados descritos geraram tal filosofia, mas foram também gerados por ela, e, nesta profícua interação, proporcionaram ao grupo de pesquisas, entre artigos, comunicações orais e painéis, bem mais de uma dezena de publicações no país e no exterior [LIMA90a; LIMA9la; LIMA9Jb; LIMA92a; LIMA93b ;TRZE89a; TRZE90b; TRZE9Ja; TRZE92a; TRZE92b; TRZE92c;VALE9la; VALE 93a;VALE93b, entre outros]. / The germ of this thesis was planted more then fifteen years ago when, in connection with a correlated albeit technologically oriented work [TRZ85af3, a paper [SCHA71a] called attention to the facts that: (i) the absence of retrapping in thermally stimulated luminescence implied a .first order kinetics mechanism, and (ii)under these circumstances, a monotonically increasing density of electrons (holes) would appear at the level to which the charge carriers would be liberated which, being the conduction (valence) band, would allow the detection of a permanent electrical conductivity, against all observed facts (without mentioning that an explanation for a transient luminescence would became a very complicated task). If this was the situation, why so much insistence in looking for numerically fitted parameters of traps and models for processes, posing questions on the order of kinetics (whose knowledge is indispensable to get meaningful values, [BRAU79b]),instead of first searching for the necessary experimental information? It was urgent to do so, the availability of an experimental equipment that would allow it was pressing. This perspective lead to the development of the SEX-Multi-purpose Experimental System in the Electro-optical Domain, described in detail in chapter six. SEX is, in brief, an integrated measurement system, operating from 80 K to 800 K under vacuum or any other chosen atmosphere, allowing to do experiments in radio-, thermo-, photo-, and electroluminescence; radio, thermo-, and photocurrents (both with and without an externally applied electric field); moreover, dielectric fosses. It is equally possible to employ SEX for sample treatments using the kinds of energy exchange involved in the above described detection techniques. Some results, obtained with the equipment at its present stage of development, are given in chapter seven. Out of its about seventy constituent parts, 70% were specially designed and built. The preoccupation initiated by Scharmann\'s paper, however, did not restrict itself to propitiate new laboratory resources. It generated directions and postures towards an optimization of the actions involved in experimental work, aiming to maximize the relationship between the obtained information and the invested efforts. To use a certain technique to investigate a given sample corresponds to put a question to Nature. The proposal of the four Principles of the second chapter is to indicate which is the best question to be asked at each step of the investigation; chapters three and four, in addition, involve relevant parts of the knowledge required for the obtained answers to be suitable understood and interpreted. It may seem strange that the content of the fifth chapter will be described only in the final paragraph of the abstract, although it is not the last chapter of this work. There is, however, a decisive reason for this: what will be found there are not results observed using SEX, but rather simultaneously parents and children of the philosophy, of the Principles for the Electro-optical Study of Defects in Materials. The presented results generated the philosophy, but were also generated by it, and, in this profitable interaction, propitiated to the research group more than a dozen publications among posters, oral communications and full papers, in Brazil and abroad [LIMA90a; LIMA9la; LIMA9Jb; LIMA92a; LIMA93b ;TRZE89a; TRZE90b; TRZE9Ja; TRZE92a; TRZE92b;TRZE92c;VALE9la;VALE 93a;VALE93b, among others].

O germe desta tese data de mais de quinze anos quando, em conexão com outro trabalho, correlato se bem que bastante voltado para a tecnologia [TRZE85a] , um artigo [SCHA71a] chamou a atenção para os fatos de que (i) a ausência de recaptura na luminescência termicamente ativada implicava um mecanismo de cinética de primeira ordem; (ii) nestas condições, ter-se-ia uma densidade eletrônica monotonicamente crescente no nível para os quais os elétrons (buracos) eram libertados; (iii) sendo tal nível a banda de condução (valência), seria detectável uma condutividade elétrica permanente, contrariamente a todas as observações experimentais (sem falar que a explicação para a transitoriedade da própria luminescência se tomaria complicada). Ora, se tal era a situação, por que se insistia tanto em buscar ajustes numéricos de parâmetros de armadilhas e de modelos de processos, questionando a ordem de cinética (cujo conhecimento é indispensável para que os valores encontrados façam sentido, [BRAU79b]), em lugar de primeiro se obterem experimentalmente as informações necessárias? Urgia fazê-lo, era premente a disponibilidade de um equipamento experimental que o permitisse. Esta perspectiva conduziu ao desenvolvimento do SEX-Sistema Experimental Multi-propósito no Domínio Eletroóptico, descrito detalhadamente no sexto capítulo. Resumidamente, trata-se de um dispositivo integrado de medição, capaz de operar na faixa de 80 K até 800 K sob vácuo ou outra atmosfera escolhida qualquer, com o qual se podem realizar experimentos de radio-, termo-, foto- e eletroluminescência, radio-, termo- e fotocorrentes elétricas (com e sem campo elétrico externo aplicado) e, ainda, perdas dielétricas; é possível igualmente nele se efetuarem tratamentos de amostras,explorando as modalidades de transferência de energia envolvidas nas técnicas de detecção acima citadas. No sétimo capítulo, estão mostrados alguns resultados obtidos com o equipamento no estágio de desenvolvimento em que ele presentemente se encontra. Das cerca de setenta partes e peças que o constituem, 70% foram especialmente projetadas e executadas. A preocupação, desencadeada pelo trabalho de Scharmann a que se aludiu acima, não se limitou, porém, a somente propiciar a disponibilidade de novos recursos para o laboratório. Ela gerou diretrizes e posturas comprometidas com a otimização das ações envolvidas no trabalho experimental, visando a maximizar a relação entre as informações obtidas e o esforço dispendido. Aplicar uma dada técnica à investigação de uma amostra corresponde a fazer uma pergunta à natureza: a proposta dos quatro Princípios descritos no segundo capítulo é indicar qual a melhor pergunta a ser feita em cada momento da investigação; complementarmente, os capítulos terceiro e quarto envolvem partes importantes do conhecimento exigido para que as respostas obtidas sejam entendidas e interpretadas adequadamente. Pode parecer curioso que, embora o capítulo quinto não seja o último deste trabalho, a descrição de seu conteúdo venha a ser feita somente no parágrafo final deste resumo. Há uma razão determinante para que assim seja: o que lá se aborda não são resultados do SEX mas, sim e ao mesmo tempo, pais e filhos da filosofia, dos Principias para o Estudo de Defeitos em Materiais no Domínio Eletroóptico. Os resultados descritos geraram tal filosofia, mas foram também gerados por ela, e, nesta profícua interação, proporcionaram ao grupo de pesquisas, entre artigos, comunicações orais e painéis, bem mais de uma dezena de publicações no país e no exterior [LIMA90a; LIMA9la; LIMA9Jb; LIMA92a; LIMA93b ;TRZE89a; TRZE90b; TRZE9Ja; TRZE92a; TRZE92b; TRZE92c;VALE9la; VALE 93a;VALE93b, entre outros]. / The germ of this thesis was planted more then fifteen years ago when, in connection with a correlated albeit technologically oriented work [TRZ85af3, a paper [SCHA71a] called attention to the facts that: (i) the absence of retrapping in thermally stimulated luminescence implied a .first order kinetics mechanism, and (ii)under these circumstances, a monotonically increasing density of electrons (holes) would appear at the level to which the charge carriers would be liberated which, being the conduction (valence) band, would allow the detection of a permanent electrical conductivity, against all observed facts (without mentioning that an explanation for a transient luminescence would became a very complicated task). If this was the situation, why so much insistence in looking for numerically fitted parameters of traps and models for processes, posing questions on the order of kinetics (whose knowledge is indispensable to get meaningful values, [BRAU79b]),instead of first searching for the necessary experimental information? It was urgent to do so, the availability of an experimental equipment that would allow it was pressing. This perspective lead to the development of the SEX-Multi-purpose Experimental System in the Electro-optical Domain, described in detail in chapter six. SEX is, in brief, an integrated measurement system, operating from 80 K to 800 K under vacuum or any other chosen atmosphere, allowing to do experiments in radio-, thermo-, photo-, and electroluminescence; radio, thermo-, and photocurrents (both with and without an externally applied electric field); moreover, dielectric fosses. It is equally possible to employ SEX for sample treatments using the kinds of energy exchange involved in the above described detection techniques. Some results, obtained with the equipment at its present stage of development, are given in chapter seven. Out of its about seventy constituent parts, 70% were specially designed and built. The preoccupation initiated by Scharmann\'s paper, however, did not restrict itself to propitiate new laboratory resources. It generated directions and postures towards an optimization of the actions involved in experimental work, aiming to maximize the relationship between the obtained information and the invested efforts. To use a certain technique to investigate a given sample corresponds to put a question to Nature. The proposal of the four Principles of the second chapter is to indicate which is the best question to be asked at each step of the investigation; chapters three and four, in addition, involve relevant parts of the knowledge required for the obtained answers to be suitable understood and interpreted. It may seem strange that the content of the fifth chapter will be described only in the final paragraph of the abstract, although it is not the last chapter of this work. There is, however, a decisive reason for this: what will be found there are not results observed using SEX, but rather simultaneously parents and children of the philosophy, of the Principles for the Electro-optical Study of Defects in Materials. The presented results generated the philosophy, but were also generated by it, and, in this profitable interaction, propitiated to the research group more than a dozen publications among posters, oral communications and full papers, in Brazil and abroad [LIMA90a; LIMA9la; LIMA9Jb; LIMA92a; LIMA93b ;TRZE89a; TRZE90b; TRZE9Ja; TRZE92a; TRZE92b;TRZE92c;VALE9la;VALE 93a;VALE93b, among others].

Th. doct.--Université de Poitiers, 2002. / Bibliogr. p. 189-201. Résumé en français et en anglais. L'ouvrage porte par erreur : ISSN 0078-3780.