Дисертації: "Er luminescence"

1

Chen, Thomas D. (Thomas Duhwa). "Energy transfer and luminescence enhancement in Er-doped silicon." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9536.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1999.
Also issued in pages.
Includes bibliographical references (leaves 143-152).
Er-doped silicon (Si:Er) is a promising light emitting material for silicon microphotonics. A study of Si:Er excitation/de-excitation mechanisms and luminescence enchancement is presented in this thesis. A model based on impurity Auger and nonradiative nmltiphonon transitions (NRl\·IPT) is shown to describe the temperature quenching of the photoluminescence (PL) intensity from 4K to 300K This model asserts that the nonradiative Auger process is mainly responsible for the temperature quenching below lOOK, and NRMPT backtransfer process is mainly responsible for the temperature quenching above lOOK. Junction photocufrei1t · spectmscopy (JPCS) measurements confirmed the existence of a backtransfer mechanism that grows with temperature in accordance to the model. In order to circumvent the onset of nonradiative transitions at higher temperatures, spontaneous emission enhancement in nrnltilayer Si/Si02 microcavities was explored as a means to increase the PL intensity. Because multilayer microcavity structures cannot be constructed using single crystal silicon, Er-doped polysilicon (poly-Si:Er) was developed as a light emitting material for these microcavities. The poly-Si:Er material exhibited a luminescence very similar to that of Er in single crystal silicon. By crystallizing poly-Si:Er from amorphous material and performing a post-anneal hydrogenation, a reasonably high PL intensity, which was limited by the excitation power, was attained. Microacavities with poly-Si:Er were fabricated and measured for the first time. Cavity quality factors of -60-300 were measured, and an Er enhancement of -20x was observed. A -lOx enhancement of a small background emission from the polysilicon was also observed. The observed enhancement factors match well with computed enhancement factors derived from electric field intensity distribution within the microcavity structure. Exploratory work in optical gain from Si:Er waveguides and vertically coupled ring resonntors was conducted. A fiber coupling technique for low temperature waveguide transmission experiments was developed for the gain experiments. The transmission spectrum of a 3-cm long waveguide was measured at temperatures down to 125K. Because the temperature could not be lowered without debonding the fiber, a net gain could not be observed in this particular waveguide. The application of stimulated emission in Si:Er devices is analyzed and discussed.
by Thomas Duhwa Chen.
Ph.D.

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2

ROGARD, STEPHANIE. "Contribution a l'etude de verres fluores dopes a l'erbium : dosage de er#3#+ dans des fibres optiques actives en zblan, mise en evidence de contraintes dans des pzg : er#3#+ evapores." Le Mans, 1997. http://www.theses.fr/1997LEMA1010.

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Les proprietes de luminescence de l'erbium dans des verres fluores sont exploitees d'une part pour effectuer des dosages de cet ion dans des fibres optiques actives en zblan, et d'autre part pour sonder l'etat de contrainte de films en pzg : er#3#+ obtenus par evaporation. Dans les deux cas, les analyses sont realisees sous microscope au moyen d'un spectrometre raman, la source excitatrice etant un laser a argon ionise. Les dosages de er#3#+ dans le zblan sont deduits d'une etude comparee de l'intensite d'une des bandes de luminescence de l'erbium (evoluant lineairement avec la puissance incidente) et l'intensite du signal raman de la matrice. Sur la gamme de concentration que nous avons exploree (inferieure a 5000 ppm en masse de erf#3), nous avons observe un comportement lineaire des rapports d'intensites en fonction de la concentration. La courbe d'etalonnage que nous avons etablie permet de determiner de facon non destructive la concentration d'erbium dans un echantillon inconnu en zblan avec une erreur relative inferieure a 12%. Ce travail a permis aussi de mettre en evidence des comportements non lineaires de l'intensite de certaines bandes de luminescence de l'erbium en fonction des puissances excitatrices. Nous en proposons une interpretation. L'etude de la luminescence de er#3#+ dans des films en pzg : er#3#+ obtenus par pvd (utilises pour realiser des guides d'onde plans) a revele des variations importantes (jusqu'a 30%) de l'intensite au cours du temps. Le phenomene est reproductible et irreversible. Nous l'avons etudie en fonction des conditions de preparation des echantillons, de la longueur d'onde, et de la puissance de la radiation excitatrice. Cet effet a ete interprete comme le temoignage de la relaxation de contraintes residuelles etablies au cours du depot. Une etude sous pression hydrostatique jusqu'a 218 kbars a permis de montrer que le signal de luminescence etait effectivement sensible a l'etat de contrainte avec en plus des modifications du profil des bandes. L'origine de ces effets est discutee.

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3

Chen, Kevin M. (Kevin Ming) 1974. "Electrical breakdown and luminescence from erbium oxide and Er-doped silicon thin films." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9816.

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4

Hussain, Syed Sajjad. "Elaboration, caractérisation structurale et luminescence de dépots AIN dopés Er obenus par PVD magnétron RF." Thesis, Nancy 1, 2010. http://www.theses.fr/2010NAN10060/document.

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Le travail présenté ici est une contribution à l’étude des propriétés de photoluminescence (PL) d’ions de terre rare (Erbium) insérés dans des matrices grand gap (AlN) de différentes morphologies et déposées sous forme de films minces. Une méthode de dépôt PVD magnétron rf a été utilisée pour obtenir des dépôts minces de nitrure d’aluminium dont les morphologies cristallines couvrent une gamme allant de la morphologie colonnaire classique jusqu’à l’état nano cristallisé et amorphe. On montre comment, plus la puissance magnétron est élevée plus les cristallites colonnaires d’AlN sont de grande dimension et comment l’application d’une polarisation négative sur les substrats de silicium permet l’obtention de dépôts nano cristallisés. Différents taux de dopage, de 0.1 à 6 at. %, sont obtenus avec une cible composite Al+Er.La PL à 1.54 [micro]m de l’atome d’Er a été étudiée en fonction des valeurs des paramètres « procédé » et donc en fonction des morphologies de AlN. Il a été montré que le maximum d'émission de PL a lieu pour un dopage de 1 at. %. L’étude montre que l'intensité de PL augmente avec la puissance magnétron et diminue avec l’intensité de polarisation des substrats. Ces deux résultats montrent que l'intensité PL est fortement corrélée à la morphologie des films. Plus les cristallites sont importantes, plus l'émission de PL est efficace. Cette corrélation entre la PL et la morphologie des matrices a permis de mettre en évidence le rôle des champs cristallins des défauts non radiatifs dans les cristallites. Le rôle des défauts a été confirmé par des mesures de luminescence résolue en temps, des mesures sur dépôts recuits et des mesures de PL à basse température. L’effet de diminution de la PL avec la température est très faible ce qui rend le matériau très prometteur pour des applications en optoélectronique et en photonique
The work presented here is a contribution to the study of the photoluminescence (PL) properties of a rare earth ions (Erbium) inserted inside wide gap matrices (AlN) of different morphologies and deposited as thin films. A physical vapour deposition magnetron rf technique has been used to obtain thin layers of aluminium nitride whose crystalline morphologies are ranging from the classical columnar morphology to the nanocrystalline state or amorphous. One shows how, the higher the magnetron power, the larger are the columnar crystallites and how the use of a negative polarization on the silicon substrates allows obtaining nano crystallized layers. Different doping rates (from 0.1 to 6 at. %) have been achieved using a Al+Er composite target.The PL of the Er atom at 1.54 [micro]m has been studied versus the process parameters and so as a function of the different AlN morphologies. It was shown that the maximum of PL emission is achieved for a rate of 1 atomic %. PL intensity was shown to increase with the magnetron power and decrease with the polarization intensity of the substrates. These two results demonstrate that PL intensity is strongly correlated to the matrix morphology. The larger the crystallites, the most efficient are the PL emission allows evidencing the role of the non radiative defects crystalline fields in the crystallites. The role of the defects was confirmed by time resolved photoluminescence measurements and by PL measurements performed on annealed samples or at low temperature. The decrease of PL with temperature is very weak, making this way the material very promising for optoelectronic and photonic applications

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5

LHOMER, CHRISTOPHE. "Proprietes electriques et optiques de terres rares (yb, er) dans les semiconducteurs iii-v. Mecanisme d'excitation de la luminescence." Rennes, INSA, 1991. http://www.theses.fr/1991ISAR0006.

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Dans le but de realiser des emetteurs infrarouge, les proprietes optiques des semiconducteurs iii-v dopes yb et er ont ete largement etudiees et sont assez bien connues. Malgre toutes ces etudes le probleme des mecanismes d'excitation de cette luminescence n'a pas ete resolu. L'etude des proprietes electriques de certains semiconducteurs iii-v dopes terre rare, nous a permis de montrer l'existence de pieges dans ces materiaux. Ces pieges crees par la terre rare ne sont pas lies a un changement d'etat de charge de l'impurete mais forment des pieges isoelectroniques. L'influence de ces pieges sur le declin de la luminescence du bord de bande met en evidence une capture efficace des porteurs photocrees. Nous proposons un modele rendant compte de ce piegeage et de la formation d'excitons lies a l'impurete terre rare. Des simulations numeriques dans le cas de yb et de er dans inp de type n nous permettent d'extraire des parametres relatifs a la formation d'excitons sur ces pieges. Ces excitons pieges peuvent, par transfert non radiatif, exciter les electrons de la couche 4f de la terre rare (tr) et cette tr emet une luminescence caracteristique des transitions internes (1 m pour yb#3#+ et 1,54 m pour er#3#+). On etablit a travers ce modele la correlation entre l'activite electrique et les proprietes optiques des terres rares dans ces semiconducteurs iii-v. Des manipulations de photoluminescence sous pression hydrostatique mettent en evidence ce transfert de l'exciton vers la terre rare et s'interpretent naturellement dans le cadre de ce modele

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6

Nascimento, Cristiane. "Propriétés structurales et optiques de verres et couches minces borates des systèmes TR : Y2O3-Al2O3-B2O3 ET TR:Y2O3-CaO-B2O3 (TR=Nd, Er)." Université Joseph Fourier (Grenoble), 2007. http://www.theses.fr/2007GRE10101.

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Dans notre travail, nous avons étudié la structure et les propriétés de luminescence des borates amorphes dopés aux terres rares (TR), contenant de l'yttrium, pour lesquels TR = Nd3+, Er3+. À cette fin, nous avons fabriqué des verres et des couches minces amorphes des systèmes Y2O3 - Al2O3, B2O3 (Y ALB) et Y2O3 - CaO - B2O3 (YCAB), que nous avons étudiés par analyse thermique (DTA, DSC, TG), diffraction de rayons X, spectroscopie vibrationnel1e (Raman et réflectance dans l'infrarouge), photoluminescence et spectroscopie de « m-lines ». Les échantillons massifs ont été synthétisés par les méthodes conventionelles de fusion/mise en forme, et les couches minces via plusieurs étapes de « spin coating » de solutions sol-gel. Les verres Y ALB présentent une température de transition vitreuse (Tg) plus élevée que les verres YCAB, respectivement 707717°C et 613-649°e. Les xerogels Y ALB obtenus à partir des solutions sol-gel présentent également un Tg, entre 713 et 716 °e. Les verres et couches minces dopés à l'erbium présentent une large bande d'émission autour de 54-66 nm pour la transition 4113/2 -> 4115/2 (1530-1535 nm). Une durée de vie maximale de 425 [MU]S a été obtenue pour les verres les moins dopés (0,1 mol%). Les verres dopés au néodyme présentent également une largeur de bande importante (36-40 nm) comparativement aux valeurs typiques pour les verres phosphates (21-25 nm). La spectroscopie m-lines a montré que les couches minces vitreuses dopées à l'erbium se comportent comme des guides d'onde planaires monomodes lorsqu'elles sont déposées sur des substrats de silice, et nous avons obtenus pour celles-ci des indices de réfraction de l'ordre de 1,59-1,65
Ln this work, we studied the structural and luminescent properties of rare earth (RE) doped amorphous borate materials containing yttrium, where RE = Nd'+, Er'+. For this purpose, bulk glasses and amorphous thin films ofthe systems Y,O, - Al,O, - B,O, (Y ALB) and Y,O, - CaO - B,O, (YCAB) were produced and their properties were investigated by thermal analysis (OTA, OSC, TG), x-ray diffraction, vibration al spectroscopy measurements (Raman and infrared reflectance), photoluminescence and m-lines spectroscopy. The bulk samples were synthesized by the conventional melting/molding method and the multilayer thin films were obtained by spin-coating sol-gel solutions. The Y ALB g1asses exhibited a higher glass transition temperature (Tg) than the YCAB glasses, 707 - 717°C and 613 - 649°C, respectively. The YALB xerogels obtained from the sol-gel solutions also presented a Tg, between 713-716°e. The glasses and thin films presented a complex borate structure, composed by a variety of superstructural units, such as metaborate rings and chains, pyroborate and orthoborate units. We found that the erbium doped glas ses and thin films presented a broad band emission of about 54 - 66 nm for the 411312 , > 4115/2 transition (1530 - 1535 nm). A maximum radiative lifetime of 425 Jls was obtained for the less doped glass samples (0,1 mol%). The neodymium doped glasses also presented a large bandwidth (38 nm), larger than values found for phosphate glasses (21-25 nm). The m-lines spectroscopy showed that the erbium glassy thin films behave as planar monomode waveguides when deposited on silica substrates, and the obtained refraction indices were about 1,59 - 1,65

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7

Ma, Lidong. "Investigation of multicolored and white light emission from IR-excited nano-particles:." Thesis, Boston College, 2021. http://hdl.handle.net/2345/bc-ir:109229.

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Thesis advisor: Baldassare Di Bartolo
Thesis advisor: Pradip Bakshi
The search for multicolored light produced by some IR laser-excited luminescent nano-powders has revealed, for laser power exceeding a threshold value, the emission of white light (WL) with black-body characteristics. I am directing my research to the study of the physical parameters that may influence the threshold power of the laser and the efficiency of the WL emission. A typical compound that I will investigate will consist of nano-powders of SrZrO3 doped with Yb. The parameters of relevance may include Yb concentration, pressure, temperature, size of nano-crystals, exciting power and wavelength of the laser, dynamical parameters such as decay and build-up patterns. The aim of my research will be both theoretical and experimental: theoretical for I will try to uncover the mechanism of the WL production and experimental for the possible application as efficient light sources of systems similar to the ones that I will investigate (oxide nano-powders doped with lanthanide or transition metal ions). The “new” light sources in the market (fluorescence lights sources, and LED lamps) beat the Edison bulbs in efficiency, but they do not produce the black-body emission of the Edison bulbs that is most pleasing to the eye. The search for efficient black-body type of sources is still on and we want to be a part of it
Thesis (PhD) — Boston College, 2021
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Physics

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8

Milori, Debora Marcondes Bastos Pereira. "Caracterização do LiNbO3:Er+3 como meio ativo para lasers de estado sólido através dos espectros de absorção/emissão polarizada e medida dos tempos de vida de luminescência." Universidade de São Paulo, 1989. http://www.teses.usp.br/teses/disponiveis/54/54131/tde-19052009-104534/.

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Este trabalho consiste na caracterização ótica de monocristais de LiNbO3: Er+3, visando a possibilidade deste sistema ser meio ativo para laser. Os resultados obtidos para absorção e emissão foram satisfatórios, sendo bastante compatíveis com os do modelo teórico adotado. O tempo de vida de luminescência das transições 4S3/2 - 4I15/2 e 4F9/2 - 4I15/2 foi medido, à temperatura ambiente e de nitrogênio líquido, mostrando que elas são possíveis candidatas a transições laser. Também foi feito um estudo sobre o comportamento das concentrações das impurezas indesejáveis OH- e Fe2+, através de tratamento térmico. O controle dessas concentrações foi feito através das técnicas de RPE e absorção ótica e os resultados mostraram que é perfeitamente possível eliminar tais impurezas de uma forma totalmente controlada.
This work consists in the optical characterization of LiNbO3:Er3+ single crystals, aiming to verify the possibility of this system being an active media for laser. The absorption and emission results were satisfactory, being compatible enough with the theoretical model adopted. The luminescence lifetime of the 4S3/2 - 4I15/2 e 4F9/2 - 4I15/2 transitions was measured at the ambient and liquid nitrogen temperature, showing that they are possible candidates for laser transitions. The behavior of the undesirable OH- and Fe2+ impurities was also studied through thermal treatment. The control of these concentrations was done using the EPR and optical absorption techniques and the results showed it is possible to eliminate such impurities in a totally controlled way.

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9

Klier, Dennis Tobias [Verfasser], and Michael Uwe [Akademischer Betreuer] Kumke. "Upconversion luminescence in Er-codoped NaYF4 nanoparticles : fundamental photophysics and optimization for life science applications / Dennis Tobias Klier ; Betreuer: Michael Uwe Kumke." Potsdam : Universität Potsdam, 2016. http://d-nb.info/1218401028/34.

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10

Morais, Evandro Augusto de [UNESP]. "Fotoluminescência e transporte elétrico em 'SNO IND. 2' dopado com os íons terras-raras 'ER POT. 3'/' e 'EU POT. 3'/'." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/100909.

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Made available in DSpace on 2014-06-11T19:31:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-02-28Bitstream added on 2014-06-13T19:40:49Z : No. of bitstreams: 1 morais_ea_dr_bauru.pdf: 1277460 bytes, checksum: 74230ee0501ddb2bea981d37cf21ce82 (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Através do processo sol-gel, foi sintetizado o material semicondutor dióxido de estanho ('SNO IND. 2') dopado com as terras-raras 'ER' e 'EU', sendo obtidas amostras na forma de xerogéis (pós) e filmes finos, neste último caso pela técnica de emersão. A introdução das terras-raras provoca desordens estruturais no material e impede o crescimento dos cristalitos, cujo tamanho varia entre 5-20NM, devido a segregação dos terras-raras na superfície das partículas, o que está relacionado a sua baixa solubilidade em 'SNO IND. 2'. A análise das propriedades ópticas mostra emissão eficiente dos íons terras-raras 'ER POT. 3'/' e 'EU POT. 3'/' quando introduzidos nesta matriz. A emissão é confirmada tanto por excitação direta destes íons, como por processos de transferência de energia, tanto correspondente ao bandgap da matriz como a transição 'INTPOT. 2 F IND. 7/2 de íon 'YB POT. 3'/' em amostras codopadas com 'ER POT. 3'/' e 'YB POT. 3'/'. A análise por fotoluminescência permite distinguir terras-raras em sítios substitucionais a 'SN POT. 4'/' ou em centros na superfície das partículas. A investigação das propriedades elétricas mostra um aumento de resistividade de até seis ordens de magnitude em relação a filmes não dopados. Isto está relacionado com o carácter aceitador de íons 'ER POT. 3'/' e 'EU POT. 3'/' em 'SNO IND. 2', que é naturalmente tipo-N, oque acarreta alta compensação de carga e também barreiras de potencial intergranulares que diminuem a mobilidade eletrônica. Foi investidada também a captura de elétrons fotoexcitados por centros de 'ER' e 'EU' termicamente ativados. À medida que se aumenta a temperatura e a concentração de 'ER' e 'EU', maior é a taxa de captura. Do modelo proposto, foram obtidos parâmetros importantes, como de captura devido aos defeitos dominantes.
The semiconductor material tin dioxide ('SNO IND. 2') has been produced by the sol-gel process, doped with the rare-earth 'ER' and 'EU'. Samples are obtained in the from of xerogels (powder) and thin films, in this latter case by the dip-coating technique. The incorporation of rare-earth ions promotes structural disorder in the material, which avoids the crystallite growth due to segregation of rare-earth ions to the surface, which is related to the low solubility in the 'SNO IND. 2' matrix. The crystallite size is in the range 5-20NM. Analysis of optical properties shows efficient emission of rare-earth ions 'ER POT. 3'/' and 'EU POT. 3'/', whem introduced in this matrix. This emission is confirmed either by direct excitation of ions, as well as by energy transfer processes, corresponding to the matrix bandgap or to the transition 'INTPOT. 2 F IND. 7/2 of íon 'YB POT. 3'/' ion in samples codoped with 'ER POT. 3'/' and 'YB POT. 3'/'. Photoluminescence spectra allow distinguishing rare-earth ions in substitutional sites of 'SN' and particles surface located centers. Investigation of electrical properties show a resitivity increase up to 6 orders of magnitude compared to undoped films. This behavior is related with the acceptor like character of 'ER POT. 3'/' and 'EU POT. 3'/' in 'SNO IND. 2', which is naturally a N-type material, leading to a high charge compensation degree and also to intergrain potential barriers that decrease the electronic mobility. It has also been investigated the capture of photogenerated electrons by ER' and 'ER' thermally activated centers. When the temperature is raised or the ER' or 'EU' concentratin is increased the capture ratebecomes faster. From a proposed model, some very relevent parameters are obtained, scu as the capture barrier due to the dominating defect.

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Morais, Evandro Augusto de. "Fotoluminescência e transporte elétrico em 'SN"O IND. 2' dopado com os íons terras-raras 'ER POT. 3'/' e 'EU POT. 3'/' /." Bauru : [s.n.], 2008. http://hdl.handle.net/11449/100909.

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Orientador: Luis Vicente de Andrade Scalvi
Banca: Sandra Helena Pulcinelli
Banca: Giancarlo Esposito de Souza Brito
Banca: Ligia de Oliveira Ruggiero
Banca: Tomaz Catunda
O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp
Resumo: Através do processo sol-gel, foi sintetizado o material semicondutor dióxido de estanho ('SN"O IND. 2') dopado com as terras-raras 'ER' e 'EU', sendo obtidas amostras na forma de xerogéis (pós) e filmes finos, neste último caso pela técnica de emersão. A introdução das terras-raras provoca desordens estruturais no material e impede o crescimento dos cristalitos, cujo tamanho varia entre 5-20NM, devido a segregação dos terras-raras na superfície das partículas, o que está relacionado a sua baixa solubilidade em 'SN"O IND. 2'. A análise das propriedades ópticas mostra emissão eficiente dos íons terras-raras 'ER POT. 3'/' e 'EU POT. 3'/' quando introduzidos nesta matriz. A emissão é confirmada tanto por excitação direta destes íons, como por processos de transferência de energia, tanto correspondente ao bandgap da matriz como a transição 'INTPOT. 2 F IND. 7/2 de íon 'YB POT. 3'/' em amostras codopadas com 'ER POT. 3'/' e 'YB POT. 3'/'. A análise por fotoluminescência permite distinguir terras-raras em sítios substitucionais a 'SN POT. 4'/' ou em centros na superfície das partículas. A investigação das propriedades elétricas mostra um aumento de resistividade de até seis ordens de magnitude em relação a filmes não dopados. Isto está relacionado com o carácter aceitador de íons 'ER POT. 3'/' e 'EU POT. 3'/' em 'SN"O IND. 2', que é naturalmente tipo-N, oque acarreta alta compensação de carga e também barreiras de potencial intergranulares que diminuem a mobilidade eletrônica. Foi investidada também a captura de elétrons fotoexcitados por centros de 'ER' e 'EU' termicamente ativados. À medida que se aumenta a temperatura e a concentração de 'ER' e 'EU', maior é a taxa de captura. Do modelo proposto, foram obtidos parâmetros importantes, como de captura devido aos defeitos dominantes.
Abstract: The semiconductor material tin dioxide ('SN"O IND. 2') has been produced by the sol-gel process, doped with the rare-earth 'ER' and 'EU'. Samples are obtained in the from of xerogels (powder) and thin films, in this latter case by the dip-coating technique. The incorporation of rare-earth ions promotes structural disorder in the material, which avoids the crystallite growth due to segregation of rare-earth ions to the surface, which is related to the low solubility in the 'SN"O IND. 2' matrix. The crystallite size is in the range 5-20NM. Analysis of optical properties shows efficient emission of rare-earth ions 'ER POT. 3'/' and 'EU POT. 3'/', whem introduced in this matrix. This emission is confirmed either by direct excitation of ions, as well as by energy transfer processes, corresponding to the matrix bandgap or to the transition 'INTPOT. 2 F IND. 7/2 of íon 'YB POT. 3'/' ion in samples codoped with 'ER POT. 3'/' and 'YB POT. 3'/'. Photoluminescence spectra allow distinguishing rare-earth ions in substitutional sites of 'SN' and particles surface located centers. Investigation of electrical properties show a resitivity increase up to 6 orders of magnitude compared to undoped films. This behavior is related with the acceptor like character of 'ER POT. 3'/' and 'EU POT. 3'/' in 'SN"O IND. 2', which is naturally a N-type material, leading to a high charge compensation degree and also to intergrain potential barriers that decrease the electronic mobility. It has also been investigated the capture of photogenerated electrons by "ER' and 'ER' thermally activated centers. When the temperature is raised or the "ER' or 'EU' concentratin is increased the capture ratebecomes faster. From a proposed model, some very relevent parameters are obtained, scu as the capture barrier due to the dominating defect.
Doutor

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12

Legrand, Jérémy. "Étude de la photoluminescence de films d'AlN dopé erbium (AlN-Er) déposés par PVD magnétron RF." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0186/document.

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Ces dernières décennies, les couches minces de semiconducteurs nitrures III-V dopés avec des terres rares ont fait l'objet d'un intérêt grandissant et ont donné lieu à de nombreuses études. En raison de leur bande interdite directe, les nitrures III-V constituent des matrices hôtes adéquates permettant la luminescence des terres rares (TR). Ainsi, en combinant les propriétés des III-V et des TR, il est possible d'envisager des applications prometteuses dans le domaine optoélectronique. Dans cette étude, l'erbium (Er) a été choisi en raison de son émission de photons à la fois dans le visible et dans l'infrarouge. Dans ce travail, les films minces d'AlN dopé à l'Er ont été élaborés avec un réacteur expérimental de pulvérisation cathodique réactive magnétron radiofréquence. Pendant le dépôt, une polarisation négative appliquée sur le substrat a permis d'obtenir des films présentant différents types de morphologies cristallines, qui ont été étudiés par diverses techniques de caractérisation telles que l'AFM, les DRX, l'ellipsométrie, le MEB, le MET. Les propriétés de luminescence des films ont été examinées expérimentalement et à l'aide d'un modèle de simulation optique par spectroscopie de photoluminescence (excitation lumineuse). Des mesures expérimentales par spectroscopie de cathodoluminescence (excitation électronique) ont également été réalisées. Le but de cette thèse était d'optimiser le procédé d'élaboration et le matériau et de mieux comprendre l'influence de la morphologie cristalline de la matrice AlN sur l'efficacité de luminescence de l'erbium. L'AlN-Er représente un système modèle et les résultats obtenus pourront être étendus aux autres TR
During the last decades, rare-earth-doped III-V thin films have been the subject of growing interest and the topic of many studies. Because III-V nitrides possess a direct gap, they are suitable host matrices to allow rare-earth (RE) luminescence. Thereby, by combining the III-V and the RE characteristics, it becomes possible to consider promising applications in the optoelectronic field. In this study, erbium (Er) was chosen because of its emission both in the visible and in the infrared range. In this work, Er-doped AlN thin films were prepared in an experimental PVD sputtering magnetron radiofrequency reactor. During the deposition, an applied negative bias on the substrate allowed to obtain different kinds of crystalline morphology of the deposited layers, which were studied by several characterization techniques such as AFM, DRX, ellipsometry, MEB, MET. Luminescence properties of the films were investigated both experimentally and with an optical model by photoluminescence (light excitation) spectroscopy. Experimental measurements by cathodoluminescence (electronic excitation) spectroscopy were also performed. This thesis aimed to optimize the elaboration process and the material and to get a better understanding of the influence of AlN host matrix crystalline morphology on the erbium luminescence efficiency. The AlN:Er system stood as a model system and the obtained results could be extended to the other RE

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13

Steveler, Émilie. "Etude des mécanismes de photoluminescence dans les nitrures et oxydes de silicium dopés aux terres rares (Er, Nd)." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0109/document.

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Ce travail de thèse est dédié à l'étude des transitions radiatives dans les matériaux de nitrure et d'oxyde de silicium dopés aux ions de terres rares (Er3+, Nd3+). La caractérisation optique des films minces élaborés par évaporation thermique est basée sur la spectroscopie de photoluminescence. Les études menées s'inscrivent dans la recherche de processus d'excitation indirecte des ions Er3+ et Nd3+ dans des matrices à base de silicium. Dans les nitrures et oxynitrures de silicium, un processus de transfert d'énergie permettant l'excitation indirecte des ions Er3+ est mis en évidence. Pour les couches minces amorphes, le couplage est attribué à des états électroniques localisés dans la bande interdite de la matrice. Pour les films recuits à haute température, les nanocristaux de silicium (nc-Si) jouent un rôle majeur dans l'excitation indirecte de l'erbium. Dans les matrices d'oxyde de silicium, l'existence de processus d'excitations directe et indirecte des ions Nd3+ est démontrée. Pour les films amorphes, l'excitation indirecte du Nd se fait via des états électroniques localisés dans la bande interdite de la matrice. Pour les films recuits au-delà de 1000 °C, les nc-Si jouent le rôle de sensibilisateurs pour les ions Nd3+. Les résultats suggèrent que l'excitation indirecte des ions Nd3+ grâce aux états localisés dans la bande interdite de la matrice pourrait être plus efficace que l'excitation via les nc-Si
This thesis is devoted to the study of radiative transitions in rare-earth (Er, Nd) doped silicon oxide and silicon nitride thin films. The optical characterization of thin films prepared by thermal evaporation is based on photoluminescence spectroscopy. In this work, we investigate indirect excitation processes of Er3+ and Nd3+ ions in silicon based materials. In silicon nitride and silicon oxinitride, an energy transfer leading to the indirect excitation of Er3+ ions is demonstrated. For amorphous samples, the sensitization of Er3+ ions is attributed to localized electronic states in the matrix bandgap. For samples annealed at high temperature, silicon nanocrystals play a major role in the indirect excitation of erbium. In silicon oxide thin films, we evidences that both direct and indirect excitation processes of Nd3+ ions occur. For amorphous samples, indirect excitation occurs thanks to localized electronic states in the matrix bandgap. For samples annealed at temperatures above 1000 °C, silicon nanocrystals are sensitizers of Nd3+ ions. Results suggest that indirect excitation thank to localized states in the matrix bandgap could be more efficient than indirect excitation thanks to silicon nanocrystals

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Câmara, Sarita Silva. "Propriedades luminescentes Upconversion do YVO4:Er,Yb aplicadas ao estudo forense de resíduo de tiro." reponame:Repositório Institucional da UnB, 2014. http://repositorio.unb.br/handle/10482/16861.

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Dissertação (mestrado)—Universidade de Brasília, Instituto de Química, Programa de Pós-Graduação em Química, 2014.
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Este trabalho trata da avaliação da utilização do ortovanadato de ítrio dopado com Er3+ e Yb3+ como marcador luminescente upconversion para a identificação de resíduo de tiro (GSR) e codificação de munições. O YVO4: 2% Er3+,Yb3+ foi sintetizado por combustão, variando-se a concentração de itérbio entre 0,5 e 8 mol%. Este material foi caracterizado por difração de raios X de pó, microscopia eletrônica de varredura, espectroscopia por dispersão de energia e espectroscopia de fluorescência, e apresentou resultados satisfatórios para ser incorporado em munições a fim de possibilitar a identificação dos GSR e codificar munições. Os materiais sintetizados com maiores concentrações de itérbio apresentaram maiores intensidades de luminescência por upconversion, sendo possível identificar visualmente a luminescência do material tanto em processo downconversion (exc = 254 nm) quanto em processo up conversion (exc = 980 nm). A incorporação desse material nas munições e as análises dos resíduo de tiro gerados indicaram que o YVO4:Er3+,Yb3+ possui as características necessárias para serem utilizados como marcadores de GSR, tais como a alta estabilidade térmica e a elevada intensidade luminescente. Também foi possível identificar visualmente a luminescência das partículas coletadas nos resíduos de tiro (exc = 254 e 980 nm). Além das propriedades ópticas, o YVO4:Er3+,Yb3+ impõe uma assinatura química aos resíduos de tiro, permitindo a sua identificação inequívoca. Estes resultados evidenciaram que o sistema YVO4:Er3+,Yb3+ apresenta alto potencial para ser utilizado como marcador para munição, de forma isolada ou associada a outro marcador - o que permite não só a identificação dos resíduos de tiro como também a codificação de munições. ______________________________________________________________________________ ABSTRACT
This work is about the evaluation of using yttrium orthovanadate doped with Er3+ and Yb3+ as an upconverting luminescent taggant for identifying gunshot residue (GSR) and encoding ammunition. The YVO4: 2% Er3+,Yb3+ was synthesized by combustion process varying the concentration of ytterbium between 0.5 and 8 mol%. This material was characterized by X-ray diffraction powder, scanning electron microscopy, energy dispersive spectroscopy and fluorescence spectroscopy, and good results were achieved in order to incorporate this material as GSR taggants and ammunition encoders. The materials synthesized with higher concentrations of ytterbium showed higher intensities of upconversion luminescence, and it was possible to visually identify the luminescence of the material in both processes such as downconversion (exc = 254 nm) and upconversion ((exc = 980 nm). The incorporation of this material in ammunition and analysis of the gunshot residues indicated that YVO4:Er3+,Yb3+ has the characteristics necessary to be used as a GSR taggant, such as high thermal stability and high luminescence intensity. It was also possible to visually identify the luminescence of the particles collected in gunshot residue (exc = 254 e 980 nm). Besides the optical properties, the YVO4:Er3+,Yb3+ imposes a chemical signature on GSR, allowing their unequivocal identification. These results showed that the YVO4:Er3+,Yb3+ system has a high potential to be used as ammunition taggant, both isolated or associated with other taggantes. This fact allows both the identification of gunshot residue and ammunition encoding.

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Ravaro, Leandro Piaggi [UNESP]. "Influência da acidez da suspensão coloidal para a geração de defeitos pontuais e emissão no infra vermelho em SnO2 dopado com Er." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/106659.

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Dióxido de estanho (snO2) é um semicondutor óxido do tipo-n, que é transparente na região do ultravioleta/visível. Possui muitas aplicações como, por exemplo, eletrodos transparente, sensores de gás, coletores e dispositivos optoeletrônicos. Quando dopado com íons terras-raras, SnO2 pode ser utilizado na confecção de dispositivos para comunicação óptica, principalmente na forma de filmes finos. A modificação do pH da suspensão coliodal, a partir do pH neutro, mostrou-se um artifício eficaz no controle das propriedades ópticas, elétricas e estruturais das amostras obtidas sem a necessidade da utilização de compostos orgânicos para a estabilização do sistema coloidal e controle do tamanho da partícula. O pH ácido favorece a formação de ligações cruzadas (Sn-O-Sn) entre as partículas, com geração de aglomerados maiores observados nas medidas de MEV/FEG e maior concentração de defeitos superficiais identificados pelos modos de vibração S1 e S2 do espectro Raman. O pH ácido também reduz a resistividade, a energia de ativação e a energia de captura dos filmes obtidos. O espectro de emissão para uma pastilha dopada com 2% de érbio, obtida com pH4, apresentou leve alteração das componentes dos níveis Stark referente aos íons Er3+ localizados na superfície desorganizada do grão. O processamento de filmes por litrografia positiva (lift-off) beneficiou a estabilidade elétrica e a reprodutividade de dados em medidas elétricas, facilitando a interferência dos resultados. Para medidas decaimento da condutividade foto-excitada com um LED de InGan (450 nm), foi possível observar valores positivo e negativo para a quantidade (Ecap-), indicando regiões distintas de temperatura com domínio da captura de elétrons por defeitos ou da mobilidade eletrônica
Tin dioxide (SnO2) is an n-type semiconductor, which is transparent in the ultraviolet/visible range. It has many applications, such as transparent electrodes, gas sensors, solar collectors and optoelectronic devices. When doped with rare-earth ions, SnO2 may be used for building optical communication devices, mainly in the form of thin films. Modification of pH of colloidad supension from neutral pH has shown an efficient tool on the control of optical, electrical and structural properties, which can be obtained without requirement of using organic compounds for stabilization of colloidal system and particle size control. Acid pH favors the formation of cross-linked bonds (Sn-O-Sn) between particles, with gernation of larger agglomerates, as observed in the SEM/FEG images and higher concentration of surface defects as identified by the vibration modes S1 and S2 of the Raman spectra. The acid pH also reduces the resitivity, the activation energy of the deeper energy level and the capture energy of obtained films. The emission spectra for a 2%Re3+- doped pellet, obtained with pH4, presents a slight variation of the Stark levels related to Er3+ ion located at the disorganized grain surface. Film processing by lift-off photolighography has led to electrical stability and data reproducibility in electrical measurements, helping the results interpretation. For measurements of decay of conductivity photo-induced by an InGaN LED (450nm), it was possible to observe positivo as well a negative values for the quantity (Ecap-), indicating distinct regions of temperature, either dominated by the electron capture by defects or by electronic mobility

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Ravaro, Leandro Piaggi. "Influência da acidez da suspensão coloidal para a geração de defeitos pontuais e emissão no infra vermelho em SnO2 dopado com Er /." Bauru, 2013. http://hdl.handle.net/11449/106659.

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Orientador: Luis Vicente de Andrade Scalvi
Banca: Fenelon Martinho Lima Pontes
Banca: Jose Humberto Dias da Silva
Banca: Andrea Simone Stucchi de Camargo Alvarez Bernardez
Banca: Virgilio de Carvalho dos Anjos
O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, PosMat , tem carater institucional e integra as atividades de pesquisa em materiais de diversos campi
Resumo: Dióxido de estanho (snO2) é um semicondutor óxido do tipo-n, que é transparente na região do ultravioleta/visível. Possui muitas aplicações como, por exemplo, eletrodos transparente, sensores de gás, coletores e dispositivos optoeletrônicos. Quando dopado com íons terras-raras, SnO2 pode ser utilizado na confecção de dispositivos para comunicação óptica, principalmente na forma de filmes finos. A modificação do pH da suspensão coliodal, a partir do pH neutro, mostrou-se um artifício eficaz no controle das propriedades ópticas, elétricas e estruturais das amostras obtidas sem a necessidade da utilização de compostos orgânicos para a estabilização do sistema coloidal e controle do tamanho da partícula. O pH ácido favorece a formação de ligações cruzadas (Sn-O-Sn) entre as partículas, com geração de aglomerados maiores observados nas medidas de MEV/FEG e maior concentração de defeitos superficiais identificados pelos modos de vibração S1 e S2 do espectro Raman. O pH ácido também reduz a resistividade, a energia de ativação e a energia de captura dos filmes obtidos. O espectro de emissão para uma pastilha dopada com 2% de érbio, obtida com pH4, apresentou leve alteração das componentes dos níveis Stark referente aos íons Er3+ localizados na superfície desorganizada do grão. O processamento de filmes por litrografia positiva (lift-off) beneficiou a estabilidade elétrica e a reprodutividade de dados em medidas elétricas, facilitando a interferência dos resultados. Para medidas decaimento da condutividade foto-excitada com um LED de InGan (450 nm), foi possível observar valores positivo e negativo para a quantidade (Ecap-), indicando regiões distintas de temperatura com domínio da captura de elétrons por defeitos ou da mobilidade eletrônica
Abstract: Tin dioxide (SnO2) is an n-type semiconductor, which is transparent in the ultraviolet/visible range. It has many applications, such as transparent electrodes, gas sensors, solar collectors and optoelectronic devices. When doped with rare-earth ions, SnO2 may be used for building optical communication devices, mainly in the form of thin films. Modification of pH of colloidad supension from neutral pH has shown an efficient tool on the control of optical, electrical and structural properties, which can be obtained without requirement of using organic compounds for stabilization of colloidal system and particle size control. Acid pH favors the formation of cross-linked bonds (Sn-O-Sn) between particles, with gernation of larger agglomerates, as observed in the SEM/FEG images and higher concentration of surface defects as identified by the vibration modes S1 and S2 of the Raman spectra. The acid pH also reduces the resitivity, the activation energy of the deeper energy level and the capture energy of obtained films. The emission spectra for a 2%Re3+- doped pellet, obtained with pH4, presents a slight variation of the Stark levels related to Er3+ ion located at the disorganized grain surface. Film processing by lift-off photolighography has led to electrical stability and data reproducibility in electrical measurements, helping the results interpretation. For measurements of decay of conductivity photo-induced by an InGaN LED (450nm), it was possible to observe positivo as well a negative values for the quantity (Ecap-), indicating distinct regions of temperature, either dominated by the electron capture by defects or by electronic mobility
Doutor

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OLIVEIRA, Alexandre Miranda de. "Síntese e caracterização de compostos do sistema x/2 Al²O³-x/2 Y²O³ (100 - x) SiO² (x=10,20,30,40 e 50) dopados com Er³+ para aplicação em fotônica." Universidade Federal de Goiás, 2010. http://repositorio.bc.ufg.br/tede/handle/tde/809.

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This work is to study the crystallization of compounds in the form of post system alumina-yttria-silica prepared by sol-gel mixed methodology and Pechini. Powders (x / 2) Y ² ³ - (X / 2) Al ² O ³ - (1-x) SiO ² (x = 0.1 0.2, 0.3, 0.4 and 0.5 mol) were doped with erbium prepared and characterized. The physical properties of composite SiO ² ¹ YO-, 5 - AlO ¹, 5 were studied by x-ray diffraction, FTIR spectroscopy, thermogravimetry, differential thermal analysis and photoluminescence measurements. It was possible to maintain the amorphous compositions at high temperatures, no crystallization below 900 ° C and the formation of phase Y ² ² O7 Si at 1100 ° C. We obtained a reasonable life time of some compositions treated at 1000 ° C. We observed the emission of green upconversion to excite the samples with high power laser. All synthesized samples exhibit photoluminescence emission and have maximum emission at 1530 nm with a width of ~ 47nm. This broad issue is a desirable property for amplifiers used in systems division multiplexing wavelengths (WDM) and suggests that Er ³ + ions are hosted in the amorphous phase.
Neste trabalho estudo-se a cristalização de compostos na forma de pós do sistema alumina-ítria-sílica preparados pela metodologia mista sol-gel e Pechini. Pós de (x/2) Y²O³-(X/2) Al²O³-(1-x) SiO² (x=0,1 0,2, 0,3, 0,4 e 0,5 em mol) dopados com érbio foram preparados e caracterizados. As propriedades físicas dos composto de SiO²-YO¹,5- AlO¹,5 foram estudadas por difração de raios-x, espectroscopia FTIR, termogravimetria, análise térmica diferencial e medidas de fotoluminescência. Foi possível manter as composições amorfas a altas temperaturas, não houve cristalização abaixo de 900° C e a formação da fase Y²Si²O7 a 1100 °C. Obtivemos um tempo de vida razóavel de algumas composições tratadas a 1000°C. Observamos a emissão verde de upconversion ao excitar as amostras com laser de alta potência. Todas as amostras sintetizadas apresentam emissão fotoluminescente e possuem máximo de emissão em 1530 nm com largura a meia altura de ~47nm. Essa emissão larga é uma propriedade desejável para amplificadores usados em sistemas de multiplexação por divisão de comprimentos de onda (WDM) e sugere que os íons Er³+ estão hospedados na fase amorfa.

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Durand, Alexandre. "Contribution à l'étude cristallochimique et optique de silicates et germanates de terres rares appartenant aux systèmes Na2O-(M,M1)III2O3 (M, M'=Nd, Eu, Gd, Er, Al, Bi;X=Si, Ge)-matériaux luminescents et scintillateurs." La Rochelle, 2002. http://www.theses.fr/2002LAROS082.

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La thématique de recherche discutée dans le présent mémoire concerne essentiellement la cristallochimie et l'étude optique de silicates et de germanates à base d'oxydes de terre rare ou de bismuth. L'analyse radiocristallographique a permis d'identifier des phases en équilibre à 1000ʿC au sein du système GeO2-(Na2O. GeO2)-(Er2O3. GeO2) appartenant au diagramme ternaire Na2O-Er2O3-GeO2. La détermination de la structure de Er(Al3/4Ge1/4)(Ge3/4Al1/4)O5 a révélé l'existence de chaînes rutiles occupées statistiquement par Al3+ et Ge4+ (% respectifs : 75 et 25 %) et de paires [(Ge,Al)2O8] formés de deux pyramides inversées partageant un côté commun à leur base carrées. Ce composé constitue l'exemple type de phases où la double distribution des cations Ge4+ sur deux sites de grande taille confère à ces ions un caractère cationique dominant, même à pression ordinaire, alors qu'ils sont censés occuper préférentiellement des cavités tétraédriques comme les cations Si4+ dans les divers mono- et di-germanates (ou silicates), notamment de terre rare. La sensibilité de la sphère de coordination de Ge4+ à l'effet de la pression a été démontré ici dans le cas de Er2Ge2O7 (où Ge4+ est tétracoordiné) qui a pu être transformé (à 800ʿC entre 2 et 3 GPa) en phase pyrochlore où Ge(IV) est localisé en sites octaédriques. En outre, la résolution des structures de NaLnSiO4. 1/4NaF (Ln = Nd, Eu, Gd, Er) a permis une meilleure clarification des filiations structurales au sein de la série AIMIIIXO4. SS (AI = cation monovalent ; MIII = lanthanide ; X = Si, Ge ; 0 = s = 0. 25 ; S = H2O, NaOH, NaF). En effet, la présente étude a montré que la majorité des monosilicates (ou monogermanates) mixtes de sodium et de terre rare (préparés par flux ou en milieu hydrothermal) ne peuvent être décrits simplement par des formules de type AIMIIIXO4. Par ailleurs, la luminescence de Eu3+ dans la phase de l'europium semble confirmer l'existence de paires Eu-Eu et ouvre les perspectives d'une étude spectroscopique plus approfondie de la série des cristaux élaborés et caractérisés au cours du présent travail, notamment les phases non-centrosymétriques (GS : I-4). Les investigations conduites sur le germanate de bismuth Bi4Ge3O12 (BGO) ont abouti à l'élaboration de fibres monocristallines de ce matériau avec des qualités optiques suffisantes permettant de démontrer leur propriétés scintillatrices après irradiation par un rayonnement ? même de faible intensité. Les prolongements prévus pour le présent travail concerneront dans l'immédiat l'étude spectroscopique et des propriétés non-linéaires (piézoélectricité, optique non-linéaire, etc. ), ainsi que l'élaboration de fibres monocristallines de BGO les plus fines et les plus longues possibles afin de mieux y caractériser le phénomène de scintillation et procéder à des tests de détection.

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Vetrone, Fiorenzo. "Luminescence spectroscopy of Er³⁺ doped inorganic nanocrystals : an investigation into their upconversion properties." Thesis, 2005. http://spectrum.library.concordia.ca/8450/1/NR04038.pdf.

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This thesis presents a detailed investigation into the spectroscopic properties of inorganic nanocrystals doped with trivalent rare earth ions. We focus on their upconversion luminescence, emission of radiation at higher energy than the pump wavelength, and evaluate the fundamental mechanisms of upconversion in the nanocrystal. We evaluate the spectroscopic properties of sesquioxide nanocrystals doped with trivalent erbium (M 2 O 3 :Er 3+ , where M = Y, Lu, or Sc) prepared by the propellant synthesis technique. Characteristic green, red, and near-infrared Er 3+ emission is observed following excitation with 488 nm in all samples under investigation. The overall luminescence intensity of the sesquioxide nanocrystals is lower compared to the microcrystalline material (bulk) as a result of the presence of high vibrational energies, 1500 and 3350 cm -1 , due to adsorbed CO 3 2- and OH - anions, respectively, which significantly increase the rate of multiphonon relaxation. The garnet (Gd 3 Ga 5 O 12 :Er 3+ ) nanocrystals, however, have considerably less surface adsorbed species, which consequently increases the luminescence intensity drastically. The upconversion of red (n exc = 650 nm) and near-infrared (n exc = 800 or 980 nm) radiation into UV, blue, green, and red emission is studied for Er 3+ ions doped in various sesquioxide (Y 2 O 3 , Lu 2 O 3 , and SC 2 O 3 ) and garnet (Gd 3 Ga 5 O 12 ) nanocrystals over a wide range of temperatures and dopant concentration is investigated. We present, for the first time, upconversion in a trivalent rare earth (RE 3+ ) doped nanocrystalline material, specifically Y 2 O 3 :Er 3+ . We show that replacing the Y 3+ cation has significant consequences on the upconversion. The upconverted luminescence of Lu 2 O 3 :Er 3+ nanocrystals have intensities that are 100x greater compared to identically doped nanocrystalline Y 2 O 3 :Er 3+ . Furthermore, Sc 2 O 3:Er 3+ nanocrystals show an enhanced red emission, which is greater than Y 2 O 3 :Er 3+ nanocrystals (with identical Er 3+ concentration) due to the smaller unit cell resulting in increased interaction between Er 3+ ions. The upconversion is observed to be dependent on the method of preparation. We explore nanocrystalline Y 2 O 3 :Er 3+ prepared via the propellant synthesis technique and a controlled hydrolysis synthesis (or wet chemical synthesis) where we observed quite diverse upconversion behavior attributed to the vastly different morphological properties of the two different nanocrystalline materials. Additionally, we investigate the effect of Yb 3+ co-doping on the upconversion luminescence of Y 2 O 3 :Er 3+ nanocrystals prepared via the two distinct synthesis routes, and observe a significant change in the mechanisms of upconversion. In the sesquioxides, the upconversion properties of the nanocrystalline material are diverse from the bulk counterpart. Finally, we attempt to ascertain if any spectroscopic changes occur in nanosized Lu 2 O 3 :Nd 3+ , Y 2 O 3 :Sm 3+ and Y 2 O 3 :Dy 3+ prepared via combustion synthesis. In all cases, the size of the particles affects the luminescence behavior

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Jiang, Ping-Ju, and 江秉儒. "Room-temperature luminescence study of Er-doped porous silicon processed by rapid thermal oxidization." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/69999370934019477315.

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碩士
國立交通大學
光電工程系所
93
We successfully employed rapid thermal oxidized porous silicon (PS) to create silicon nanocrystals (nc-Si). In order to observe the size and the characteristics, experiments on different samples were investigated via transmission electron microscope (TEM)、Raman scattering and photoluminescence. After that, we doped Er ions into silicon rich SiO2 (SRSO) structure and successfully observed the infrared photoluminescence at 1.54μm from Er ions. The relations between infrared photoluminescence and average size of nc-Si were discussed in this study. In this work, we controlled different current density to vary the silicon porosity. The different average size of nc-Si were formed by changing the silicon porosity and rapid thermal oxidization. We observe the red-shift of Raman scattering and the blue-shift of visible photoluminescence from the average size of nc-Si. The intensity of infrared photoluminescence at 1.54μm from Er ions would increase as the decreasing of the average size of nc-Si. This fact means that the Er ions are excited by energy transfer process from the excited nc-Si and the conversion efficiency has relations with the average size of nc-Si.

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Rinkel, Thorben. "Untersuchung der Keimbildung und Fluoreszenz von NaYF4:Yb,Er-Nanopartikeln mit Größen von unter 10nm." Doctoral thesis, 2016. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2016021814264.

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In dieser Arbeit ist das Wachstumsverhalten von unter 10nm großen, aufwärtskonvertierenden NaYF4-Nanokristallen der hexagonalen und kubischen Phase untersucht worden. Die Ostwald-Reifung solcher Partikel in Ölsäure/1-Octadecen führt zu einer Verbreiterung der Partikelgrößenverteilung, falls das Kolloid nur aus Partikeln einer Kristallphase besteht. Eine schmale Teilchengrößenverteilung tritt nur dann auf, wenn die Partikel der b-Phase in Anwesenheit eines Überschusses von Partikeln der a-Phase wachsen. Solche binären Gemische aus Partikeln der a- und b-Phase entstehen, sobald Kolloide aus Partikeln der a-Phase für eine genügend lange Zeit erhitzt werden, denn bei hohen Temperaturen nukleieren Keime der b-Phase nach einer gewissen Zeit. Weil durch die Anzahl der Keime die finale Partikelgröße des Produkts der b-Phase bestimmt wird, ist eine Kontrolle der Nukleation wichtig um die finale Partikelgröße steuern zu können. Es wird gezeigt, dass die Anzahl der Keime der b-Phase stark abhängig von der Zusammensetzung der Partikel der a-Phase ist, die als Ausgangsmaterial verwendet werden. Die a-Phase ist dafür bekannt Na1−xYF4−x-Mischkristalle mit Zusammensetzungen von x=0 bis x=4/9 zu bilden. Bei natriumarmen Partikeln der a-Phase entstehen eine geringe Anzahl an Keimen der b-Phase, wobei Partikel der a-Phase mit einem hohen Gehalt an Natrium eine große Anzahl an Keimen bilden. Durch die Ausnutzung dieser Abhängigkeit und der dementsprechenden Modifizierung der Synthese der Partikel der a-Phase, können in Ölsäure/1-Octadecen kleine, phasenreine b-NaYF4:Yb,Er-Partikel mit Größen von unter 6 nm, sowohl als auch deutlich größere Partikel erhalten werden. Weiterhin wird gezeigt, dass Mischungen von a- und b-Partikeln auch sehr gut für die Synthese von Kern/Schale-Partikeln geringer Größe geeignet sind. Durch die Reaktion von Natriumoleat, Seltenerdoleat und Ammoniumfluorid werden zunächst etwa 5nm große b-NaYF4:Yb,Er-Kernpartikel gebildet, wobei ein hohes Verhältnis von Natrium- zu Seltenerdionen die Nukleation einer großen Anzahl von Keimen der b-Phase begünstigt. Anschließend wird eine etwa 2nm dicke Schale aus b-NaYF4 aufgewachsen, wobei 3–4nm große a-NaYF4-Partikel als Vorläuferpartikel für das Schalenmaterial dienen. Im Gegensatz zu den Kernpartikeln werden diese Partikel der a-Phase jedoch mit einem geringen Verhältnis von Natrium- zu Seltenerdionen hergestellt, welches die unerwünschte Nukleation von b-NaYF4-Partikeln während des Schalenwachstums wirksam unterdrückt. Diese neue Methode zur Herstellung sehr kleiner aufwärtskonvertierender Kern/Schale-Nanokristalle kommt ohne zusätzliche Kodotierung der Kernpartikel aus und liefert Partikel im Gramm-Maßstab.

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Дисертації з теми "Er luminescence"

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