Bibliografias temáticas / Germanium poreux

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Literatura científica selecionada sobre o tema "Germanium poreux"

Autor: Grafiati

Publicado: 21 de dezembro de 2024

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Artigos de revistas sobre o assunto "Germanium poreux"

Chubenko, E. B., N. L. Grevtsov, V. P. Bondarenko, I. M. Gavrilin, A. V. Pavlikov, A. A. Dronov, L. S. Volkova e S. A. Gavrilov. "RAMAN SPECTRА OF SILICON/GERMANIUM ALLOY THIN FILMS BASED ON POROUS SILICON". Journal of Applied Spectroscopy 89, n.º 5 (21 de setembro de 2022): 614–20. http://dx.doi.org/10.47612/0514-7506-2022-89-5-614-620.

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The regularities of composition changes of silicon/germanium alloy thin films formed on a monocrystalline silicon substrate by electrochemical deposition of germanium into a porous silicon matrix with subsequent rapid thermal annealing (RTA) at a temperature of 750–950°C are studied. An analysis of the samples by Raman spectroscopy showed that an increase of RTA temperature leads to a decrease in the germanium concentration in the formed film. A decrease of the RTA duration at a given temperature makes it possible to obtain films with a higher concentration of germanium and to control the composition of thin silicon/germanium alloy films formed by changing the temperature and duration of RTA. The obtained results on controlling the composition of silicon/germanium alloy films can be used to create functional electronic devices, thermoelectric power converters, and optoelectronic devices.

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Garralaga Rojas, Enrique, Jan Hensen, Jürgen Carstensen, Helmut Föll e Rolf Brendel. "Porous germanium multilayers". physica status solidi (c) 8, n.º 6 (7 de abril de 2011): 1731–33. http://dx.doi.org/10.1002/pssc.201000130.

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Grevtsov, Nikita, Eugene Chubenko, Vitaly Bondarenko, Ilya Gavrilin, Alexey Dronov e Sergey Gavrilov. "Germanium electrodeposition into porous silicon for silicon-germanium alloying". Materialia 26 (dezembro de 2022): 101558. http://dx.doi.org/10.1016/j.mtla.2022.101558.

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Amato, G., A. M. Rossi, L. Boarino e N. Brunetto. "On the role of germanium in porous silicon-germanium luminescence". Philosophical Magazine B 76, n.º 3 (setembro de 1997): 395–403. http://dx.doi.org/10.1080/01418639708241102.

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Li, Xiu, Wei Guo, Qian Wan e Jianmin Ma. "Porous amorphous Ge/C composites with excellent electrochemical properties". RSC Advances 5, n.º 36 (2015): 28111–14. http://dx.doi.org/10.1039/c5ra02459e.

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Xu, Jing, Thanh-Dinh Nguyen, Kai Xie, Wadood Y. Hamad e Mark J. MacLachlan. "Chiral nematic porous germania and germanium/carbon films". Nanoscale 7, n.º 31 (2015): 13215–23. http://dx.doi.org/10.1039/c5nr02520f.

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Co-assembly of cellulose nanocrystals (CNCs) with germanium(iv) alkoxide in a mixed solvent system produces chiral nematic photonic GeO₂/CNC composites, which were converted to semiconducting, mesoporous GeO₂/C and Ge/C replicas.

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Yin, Huayi, Wei Xiao, Xuhui Mao, Hua Zhu e Dihua Wang. "Preparation of a porous nanostructured germanium from GeO2via a “reduction–alloying–dealloying” approach". Journal of Materials Chemistry A 3, n.º 4 (2015): 1427–30. http://dx.doi.org/10.1039/c4ta05244g.

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Rojas, E. Garralaga, J. Hensen, J. Carstensen, H. Föll e R. Brendel. "Lift-off of Porous Germanium Layers". Journal of The Electrochemical Society 158, n.º 6 (2011): D408. http://dx.doi.org/10.1149/1.3583645.

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Isaiev, M., S. Tutashkonko, V. Jean, K. Termentzidis, T. Nychyporuk, D. Andrusenko, O. Marty, R. M. Burbelo, D. Lacroix e V. Lysenko. "Thermal conductivity of meso-porous germanium". Applied Physics Letters 105, n.º 3 (21 de julho de 2014): 031912. http://dx.doi.org/10.1063/1.4891196.

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Platonov, Nikolay, Nail Suleimanov e Valery Bazarov. "Study of the electrophysical properties of nanostructured porous germanium as a promising material for electrodes of electrochemical capacitors". E3S Web of Conferences 288 (2021): 01073. http://dx.doi.org/10.1051/e3sconf/202128801073.

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Electrochemical capacitors (ECC) are a fast charging devices, with high power density, capacity and increased life time. Nanostructured semiconductors are now considered as the promising materials for electrodes of such devices due to its conductive properties and effective surface. One of such materials is the porous germanium which can be used as an electrode in electrochemical capacitors. In this article the novel approach based on the method of ion implantation was developed to grow these structures. This method allows to obtain a structures up to 1 μm thick. The object of this work was the investigation of the electrophysical characteristics of samples of nanostructured porous germanium (Ge) depending on the implantation dose and surface morphology. The scientific novelty of this research lies in the search the structures with the highest effective surface area and electronic conductivity, capable of multiplying the energy capacity and specific power of ECC. Methods: The samples of amorphous Ge were grown on dielectric single-crystal substrates of Al2O3. The thickness of samples was 600 and 1000 nm. The magnetron sputtering and ion implantation methods were used to growth these structures. The irradiation with Ge+ ions produced with an energy of 40 keV and the range of implantation doses varied from 2·1016 to 12•1016 ion / cm2. The study of electrical properties was carried out on the Hall installation HL55PC at the NPP KVANT in Moscow. The following parameters were measured: the sheet concentration of carriers in the near-surface layer, electrical resistance, mobility of the charge carriers, Hall coefficient. As a result, the dependences of carriers concentration and their mobility as the function of the implantation dose and thickness of the samples of nanostructured porous germanium were determined, and the results were analyzed. Results: It was found that ion implantation of single-crystal germanium leads to an increase in the carrier concentration in the near-surface layer. To sum up, the most suitable material as an electrode for ECC is the porous germanium with the maximum dose of ion implantation and the largest thickness. The maximum sheet carrier concentration that was obtained in the study for Ge is 1017 cm-2.

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Mais fontes

Teses / dissertações sobre o assunto "Germanium poreux"

Mathiaud, Romain. "Synthèse et structuration de disulfure de germanium en présence de liquides ioniques et de tensioactifs". Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20088/document.

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L'obtention de manière contrôlée de matériaux chalcogénures nanostructurés et possédant une surface spécifique importante ou fonctionnalisée est un défi très intéressant. En alliant une surface spécifique élevée à la polarisabilité des surfaces chalcogénures ou en élaborant des matériaux fonctionnalisés, on peut espérer une percée dans de nombreux domaines comme la catalyse, la séparation gazeuse, l'électrochimie, le photovoltaïque ou l'optique... L'objectif de cette thèse était de développer des voies de synthèse du disulfure de germanium (GeS2) par chimie douce à température et pression ambiantes. Pour cela, nous avons utilisé deux agents sulfurants, le sulfure de dihydrogène (H2S) et le thioacétamide que nous avons fait réagir avec du tétraéthoxyde de germanium en présence d'un solvant. Les synthèses ont été réalisées en l'absence ou en présence d'un structurant, le plus souvent un liquide ionique (LI). Les synthèses sans structurant ont permis l'obtention de nanoparticules de GeS2 amorphes ou nano-organisées de 20 à 35 nm de diamètre et de surface spécifique intéressante (320 m2.g-1 avec H2S, 270 m2.g-1 avec le thioacétamide). Les synthèses réalisées en présence de LI conduisent à des matériaux hybrides contenant GeS2 et le cation du LI utilisé, de formule générale 0.2GeS2-0.8 cation organique. Les particules obtenues de taille micrométrique et présentant de très faibles surfaces spécifiques ont une morphologie qui dépend de la nature du cation organique impliqué dans la synthèse (sphères ou roses des sables). Des mesures XPS montrent la présence de liaisons Ge-S- au sein de l'hybride. L'utilisation de lithium de bis(trifluorométhanesulfonyl)imide nous a conduit à synthétiser un matériau GeS2-Li dont la conductivité de ~10-10 S.cm-1 est celle d'un sel ionique. En l'absence de solvant et en faisant jouer au LI le rôle de solvant et de structurant, nous avons pu préparer le premier iono-chalcogel qui, après optimisation, pourrait conduire à un matériau poreux. Par ailleurs, l'utilisation d'un structurant non ionique, l'hexadecylamine (HDA), au-delà de sa concentration micellaire critique, a conduit à l'obtention d'un matériau hybride nanométrique (environ 15 nm) qui possède non seulement une surface spécifique intéressante (130 m2.g-1) mais surtout une porosité intra-granulaire. En résumé, ce premier travail exploratoire nous a permis d'obtenir, selon le procédé de chimie douce choisi, du disulfure de germanium sous forme soit de nanoparticules aux surfaces spécifiques intéressantes, soit de particules présentant une certaine porosité intragranulaire, soit de matériaux hybrides où un cation organique interagit avec GeS2
The controlled elaboration of nanostructured chalcogenides with high specific area or functionalized surface is an interesting challenge. Breakthrough in various domains such as catalysis, gas separation, electrochemistry, photovoltaics or optics can be achieved by the production of chalcogenide materials with functionalized surface or high specific area coupled with high polarisability.The aim of the thesis was to develop new soft chemistry routes for the synthesis of germanium disulfide at room temperature and pressure. Two sulfur precursors, i.e. hydrogen sulfide (H2S) and thioacetamide, and a germanium precursor, the tetraethoxigermanium were used for the syntheses. The syntheses were carried out either in the presence or in the absence of a template, in most case an ionic liquid (IL).Syntheses without templating agent led to amorphous or nano-organized GeS2 nanoparticles of 20 to 35 nm in diameter and interesting specific areas (320 m2.g-1 with H2S, 270 m2.g-1 with thioacetamide). Hybrid materials comprising GeS2 and LI cation with a general formula 0.2GeS2-0.8 organic cation were obtained in the presence of IL. The obtained particles of nanometric sizes and with hardly any specific area have a morphology that depends on the nature of the organic cation present during the synthesis, i .e. spheres or gypsum rosette-like particles. XPS measurements indicate the presence of Ge-S- bonds in the hybrid material. The use of lithium de bis(trifluorométhanesulfonyl)imide led to the elaboration of a GeS2-Li material which conductivity of ~10-10 S.cm-1 is that of an ionic salt.A first iono-chalcogel which could lead after optimization to a porous chalcogenide has been elaborated when using the IL as both the solvent and the templating agent and in the absence of any other solvent. The use of hexadecilamine (HDA) above its critical micellar concentration, led to hybrid nanoparticles of 15 nm in size with interesting specific area (130 m2.g-1) but also intra-granular porosity.In conclusion, this exploratory work led to the elaboration of GeS2 either as naoparticles with high specific area or particles with intragranular porosity or finally hybrid materials with GeS2 interacting with an organic cation, the final product depending upon the chosen soft chemistry route.Keywords: chalcogenide, ionic liquid, organic-inorganic hybrid, morphology, soft chemistry

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Jaafar, Abdallah. "Développement de matériaux poreux pour des applications de détection en optique intégrée dans le moyen infrarouge". Electronic Thesis or Diss., Université de Rennes (2023-....), 2024. http://www.theses.fr/2024URENS043.

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Les capteurs optiques intégrés basés sur des dispositifs optiques guidés en matériaux poreux peuvent détecter efficacement et sélectivement des molécules polluantes présentes dans l’eau, l’air et l’environnement. La structure poreuse permet aux molécules à détecter de s’infiltrer dans les pores, ce qui permet une détection volumique. Cette caractéristique exalte la sensibilité d’un capteur optique intégré et offre aussi la possibilité de détecter une très faible quantité de molécules. Dans ce travail, deux matériaux transparents dans le moyen infrarouge (MIR) ont été étudiés pour le développement de guides d’onde optiques intégrés : le silicium poreux (SiP) et le germanium poreux (GeP). Le SiP est produit par anodisation électrochimique et peut être utilisé jusqu’à la longueur d’onde de 8 µm. Des guides d’onde plan et ridge en SiP ont été développés à partir de substrats de silicium de type P faiblement ou fortement dopés. L’effet de traitement thermique d’oxydation sur le guidage a été étudié. Un test de transduction sur la détection de CO₂ dans le MIR autour de la longueur d’onde de 4.3 µm a été réalisé. Le GeP, quant à lui, est produit par gravure électrochimique bipolaire et permet d’étendre la plage de détection jusqu’à la longueur d’onde de 14 µm. Ce matériau, utilisé pour le développement d’un capteur optique intégré, constitue ainsi un atout considérable étant donné que la plupart des molécules polluantes présentent une bande d’absorption dans le MIR. Des couches homogènes de faibles épaisseurs ont pu être réalisées. Un premier test d’élaboration d’un miroir de Bragg a aussi été effectué
Integrated sensors based on guided optical devices can efficiently and selectively detect pollutant molecules present in water, air, and environment. The porous structure allows the targeted molecules to penetrate into the pores, leads to volume detection. This characteristic greatly enhances the sensitivity and the ability to detect a very small number of molecules. In this study, two mid-infrared (mid-IR) transparent materials were investigated for the evelopment of integrated optical waveguides: porous silicon (PSi) and porous germanium (PGe). PSi is produced by electrochemical anodization and can be used up to a wavelength of 8 µm. PSi-based planar and ridge waveguides were developed from lightly or heavily P-doped silicon substrates. The effect of thermal oxidation treatment on the optical properties of the waveguides was investigated. Transduction tests were carried out to detect carbon dioxide (CO₂) in the mid-IR at around 4.3 µm wavelength. On the other hand, PGe is produced using bipolar electrochemical etching, extending the detection range to a wavelength of 14 µm. This material offers a considerable advantage for the development of an integrated optical sensor, as most polluting molecules have an absorption band in the mid-IR spectral range. Thin and homogeneous PGe layers were obtained. An initial test for the fabrication of a Bragg mirror was also conducted

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Wang, Xu-xu. "Modification de solides micro - et méso - poreux par chimie organométallique de surface". Lyon 1, 1999. http://www.theses.fr/1999LYO10327.

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L'objectif de ce travail de these etait de modifier les proprietes de tamis moleculaires par reaction avec des complexes organometalliques. Des etudes preliminaires avaient ete realisees sur mordenite et sur cloverite. Nous avons etendu ces etudes a toute une serie de composes micro- et mesoporeux, telle la zsm-5, la faujasite y et mcm-41. Par reaction avec le tetrabutyl germanium il est possible de modifier toutes les entrees de pores de la zsm-5 sans toucher a la surface interne, ce qui entraine des modifications des proprietes d'adsorption des hydrocarbures. Cependant, la reaction est moins propre que sur la mordenite et il y a formation d'un melange d'especes -ger x, x = 1 a 3. Dans ce cas de la zeolithe hy, l'objectif etait de modifier une partie des canaux et cages (surface interne), afin de pouvoir ensuite, par echange ionique introduire des metaux de transition. C'est pour cette raison que le tetramethyl etain a ete choisi. Nous avons pu montrer que ce complexe organometallique reagit des 80\c avec les groupes hydroxyles pour donner des fragments -snme 3 greffes dans les supercages. Nous avons aussi etudie la modification de silices mesoporeuses par reaction avec des complexes organometalliques. C'est ainsi que nous avons pu montrer que lorsque une silice mesoporeuse est modifiee par reaction avec des complexes organometalliques de l'etain, ses proprietes d'adsorption vis-a-vis des hydrocarbures sont totalement modifiees : les interactions adsorbat-adsorbant, de type oh-ch dans le materiau non modifie, sont de type ch-ch dans le materiau modifie, ce qui se traduit par des isothermes d'adsorption tres differentes. Nous avons aussi compare les silices mesoporeuses contenant du zirconium introduit lors de la synthese a des composes ou le zircocnium est introduit sur une silice mesoporeuse par reaction avec un complexe organometallique de type zrnp 4 et hydrolyse subsequente. Les proprietes, notamment acides, de ces deux types de solides sont completement differentes.

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Buttard, Denis. "Étude structurale du silicium poreux de type p par diffraction haute résolution des rayons X". Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10141.

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La premiere partie de ce travail a ete consacree a l'etude, par diffraction des rayons x, des deformations engendrees par des effets de surface. Nous avons notamment mis en evidence, grace a des mesures in situ sous ultra vide, que la dilatation qui existe pour un echantillon fraichement prepare est due aux liaisons si-h#x presentes a la surface des cristallites de silicium. Nous avons d'autre part etudie la passivation du silicium poreux par oxydation des cristallites de silicium qui se traduit par une dilatation supplementaire a la dilatation originelle du parametre de maille cristallin. Le remplissage des pores par un depot de germanium a enfin ete etudie, montrant une epitaxie du germanium jusqu'au fond des pores. La deuxieme partie de ce travail de these presente les mesures de diffusion diffuse aux pieds des pics de bragg, et les informations structurales qui en resultent, pour des echantillons fraichement prepares. Pourles couches de type p#-, les cristallites sont isotropes avec un diametre de l'ordre de 3 nm. Les couches de type p#+ se presentent de maniere differente avec des cristallites anisotropes de 10 nm diametre. Une contribution isotrope peu intense analogue au p#- est aussi presente, ce qui suggere la presence de petits objets egalement dans le p#+. La derniere partie de ce travail regroupe l'etude des couches minces et des super-reseaux de silicium poreux, par diffraction et reflectivite des rayons x. Une analyse quantitative des donnees a ete realisee systematiquement par simulation numerique. Les couches minces sont de bonne qualite bien cristallines et la rugosite des interfaces reste faible. Un resultat important est l'existence d'une couche de transition de 10-20 nm a l'interface poreux/massif, ainsi que la presence d'un film de surface de faible porosite dans le cas du materiau de type p#+. L'analyse des super-reseaux demontre leur bonne qualite, qui se manifeste par la presence de pics satellites tres fins associe a la super-structure. Le changement de porosite entre les couches s'etale ici encore sur une zone de transition de l'ordre de 14 nm.

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Tutashkonko, Sergii. "Élaboration du Ge mésoporeux et étude de ses propriétés physico-chimiques en vue d'applications photovoltaïques". Thèse, Université de Sherbrooke, 2013. http://hdl.handle.net/11143/6145.

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Le sujet de cette thèse porte sur l'élaboration du nouveau nanomatériau par la gravure électrochimique bipolaire (BEE) -- le Ge mésoporeux et sur l'analyse de ses propriétés physico-chimiques en vue de son utilisation dans des applications photovoltaïques. La formation du Ge mésoporeux par gravure électrochimique a été précédemment rapportée dans la littérature. Cependant, le verrou technologique important des procédés de fabrication existants consistait à obtenir des couches épaisses (supérieure à 500 nm ) du Ge mésoporeux à la morphologie parfaitement contrôlée. En effet, la caractérisation physico-chimique des couches minces est beaucoup plus compliquée et le nombre de leurs applications possibles est fortement limité. Nous avons développé un modèle électrochimique qui décrit les mécanismes principaux de formation des pores ce qui nous a permis de réaliser des structures épaisses du Ge mésoporeux (jusqu'au 10 ?m ) ayant la porosité ajustable dans une large gamme de 15% à 60%. En plus, la formation des nanostructures poreuses aux morphologies variables et bien contrôlées est désormais devenue possible. Enfin, la maîtrise de tous ces paramètres a ouvert la voie extrêmement prometteuse vers la réalisation des structures poreuses à multi-couches à base de Ge pour des nombreuses applications innovantes et multidisciplinaires grâce à la flexibilité technologique actuelle atteinte. En particulier, dans le cadre de cette thèse, les couches du Ge mesoporeux ont été optimisées dans le but de réaliser le procédé de transfert de couches minces d'une cellule solaire à triple jonctions via une couche sacrificielle en Ge poreux.

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Garchery, Laurent. "Fabrication et étude des propriétés physiques des nanostructures Si/SiGe : application aux nouveaux dispositifs". Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10232.

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La technologie de la microelectronique silicium beneficie aujourd'hui d'investissements massifs et continus. Tout porte a croire que les excellentes proprietes du systeme si/sio#2 assureront la perennite du si pendant encore de nombreuses annees. Le developpement de nouveaux materiaux pouvant ameliorer les performances des dispositifs a base de si est donc encourage. En particulier, l'heterosysteme si/sige apparait comme le meilleur candidat pour le developpement d'une technologie a heterojonction a base de si. De tels materiaux doivent cependant etre compatibles avec les temperatures de recuit utilisees dans la technologie si. Les deux principaux dispositifs electroniques dans lesquels l'utilisation du sige est envisagee sont le transistor bipolaire et le transistor a effet de champ. Dans le cas du transistor a effet de champ, l'interet du sige est d'ameliorer les proprietes de transport parallele au plan des couches. Cette these est consacree a l'etude experimentale de ces proprietes ainsi qu'a l'analyse et a la comprehension du fonctionnement des heteronjonctions si/sige. Nous rappelons tout d'abord les proprietes de structure de bandes des heterosystemes contraints si/sige ainsi que la methode de mesure par effet hall que nous avons utilisee. Une etude de l'evolution thermique des proprietes de transport et de confinement de modulations de dopage si/sige de type p est ensuite presentee. Puis, nous analysons les proprietes de transport electronique des heterostructures si/sige elaborees sur un pseudo-substrat de sige relaxe. Le principe de fonctionnement specifique des dispositifs mos a canal enterre en sige est ensuite mis en evidence experimentalement. Nous constaterons finalement que les caracteristiques electriques des dispositifs mos a base de si peuvent etre ameliorees par l'introduction d'un canal enterre en sige

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FUGATTINI, Silvio. "Binder-free porous germanium anode for Li-ion batteries". Doctoral thesis, Università degli studi di Ferrara, 2019. http://hdl.handle.net/11392/2488081.

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To develop high energy density lithium ion batteries, the use of new electrode materials is required. Germanium is among the possible alternatives to the most commonly used anode, graphite (372 mAh/g), thanks to its four-times higher theoretical gravimetric capacity (1600 mAh/g). Here is presented a two-step method to produce a binder-free porous germanium anode, depositing the semiconductor on metallic substrates by means of Plasma Enhanced Chemical Vapour Deposition (PECVD) and subsequently performing an electrochemical etching with hydrofluoric acid to create a porous structure. The Ge-based electrode attained a capacity of 1250 mAh/g at a current rate of 1C (1C=1600 mA/g) and retained a stable capacity above 1100 mAh/g for more than 1000 cycles tested at different C-rates up to 5C. Both deposition and etching techniques are scalable for industrial production, whose fields of application could be aerospace or medical applications, due to the high cost of germanium as a raw material.
Per sviluppare batterie agli ioni di litio ad alta densità energetica, è necessario l’utilizzo di nuovi materiali elettrodici. Il germanio è una delle possibili alternative all’anodo più comunemente impiegato, la grafite (372 mAh/g), grazie alla sua capacità gravimetrica teorica quattro volte maggiore (1600 mAh/g). In questo lavoro viene presentato un processo in due fasi per realizzare un anodo in germanio poroso privo di legante (binder), realizzando film di semiconduttore su substrati metallici mediante deposizione chimica da fase vapore assisitita da plasma (PECVD) ed effettuando successivamente un attacco elettrochimico con acido fluoridrico per creare una struttura porosa. L’elettrodo in germanio poroso ha raggiunto una capacità di 1250 mAh/g ad una velocità di carica/scarica pari ad 1C (1C = 1600 mA/g) mantenendo, inoltre, una capacità stabilmente superiore a 1100 mAh/g per più di 1000 cicli a diversi C-rate fino a 5C. Sia la tecnica di deposizione che quella di attacco chimico sono scalabili per la produzione industriale, i cui possibili campi di applicazione sono il settore aerospaziale o medico, a causa dell’elevato costo del germanio come materia prima.

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Huang, Xuezhen. "Fabrication and optical properties of (I) erbium-doped nanowires containing germanium and/or zinc oxide and (II) porous germanium nanowires". [Fort Worth, Tex.] : Texas Christian University, 2010. http://etd.tcu.edu/etdfiles/available/etd-04282010-134727/unrestricted/Huang.pdf.

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Kitschke, Philipp, Marc Walter, Tobias Rüffer, Andreas Seifert, Florian Speck, Thomas Seyller, Stefan Spange et al. "Porous Ge@C materials via twin polymerization of germanium(II) salicyl alcoholates for Li-ion batteries". Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-197302.

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The germylenes, germanium(II) 2-(oxidomethyl)phenolate (1), germanium(II) 4-methyl-2-(oxidomethyl)phenolate (2) and germanium(II) 4-bromo-2-(oxidomethyl)phenolate (3) were synthesized and their thermally induced twin polymerization to give organic–inorganic hybrid materials was studied. The compounds 1–3 form oligomers including dimers, trimers and tetramers as a result of intermolecular coordination of the benzylic oxygen atom to germanium. The structural motifs were studied by single crystal X-ray diffraction analysis and DFT-D calculations. Thermally induced twin polymerization of these germylenes gave hybrid materials based on germanium-containing phenolic resins. Carbonization of these resins under reductive conditions resulted in porous materials that are composed of germanium and carbon (Ge@C materials), while oxidation with air provided non-porous germanium dioxide. The porous Ge@C materials were tested as potential anode materials for rechargeable Li-ion batteries. Reversible capacities of 540 mA h g−1 were obtained at a current density of 346 mA g−1 without apparent fading for 100 cycles, which demonstrates that germanium is well accessible in the hybrid material
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CALABRESE, Gabriele. "Relaxed germanium epilayers on porous silicon buffers for low dislocation content Ge on Si virtual substrates". Doctoral thesis, Università degli studi di Ferrara, 2015. http://hdl.handle.net/11392/2389093.

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While silicon represents the dominant material in the semiconductor industry, the continuous improvement in the performance of Si based devices is reaching its upper bound due to the approaching of insuperable physical limitations intrinsic to Si, which requires the introduction of new semiconductor materials and the development of new assembly techniques to guarantee the future performance improvement and reduction in fabrication costs. The integration of high-quality germanium epilayers on Si substrates has received great attention from the semiconductor community due to the chance to extend the range of performance offered by Si-based technology by taking advantage of both the superior properties of Ge such as a higher carrier mobility, a lattice constant close to that of GaAs which enables III-V epitaxy and a quasi-direct bandgap, and of the possibility of strain and bandgap engineering offered by the formation of a heterojunction. To overcome the 4.2% lattice constant mismatch existing between Ge and Si which hamper the direct integration approach, this thesis investigates a novel technique for the realization of high-quality Ge on Si virtual substrates (VSs), consisting in the introduction of a porous silicon (pSi) buffer layer in between Ge and Si. pSi is a versatile, self-assembled, nanomaterial which can be realized at very high growth rates through electrochemical etching of Si. Thanks to its reduced Young’s and shear moduli pSi can deform during epitaxy, potentially alleviating part of the lattice mismatch between Ge and Si and reducing the density of misfit dislocations and associated threading segments necessary for complete Ge relaxation. Together with the very high throughput of the anodization process, other fundamental advantages of the proposed approach are its low cost, its simple scalability to large area Si substrates and the possibility to lift-off the grown epilayers from the starting substrates, giving Ge on pSi VSs the possibility to outperform other existing techniques for Ge integration on Si. During the course of this work, several Ge on pSi VSs have been grown through low energy plasma enhanced chemical vapor deposition (LEPECVD) technique, and the resulting crystalline quality has been compared to that of Ge on Si VSs. Using X-ray diffraction techniques, together with electron microscopy analysis and selective etching techniques, it will be shown how the main physical parameters of pSi buffers affect the crystalline quality of Ge heteroepilayers. Finally, it will be demonstrated that strong threading dislocation reduction is possible in Ge grown on low porosity pSi buffers compared to Ge on bulk Si, at parity of experimental conditions, and the main mechanisms responsible for crystalline quality improvement in Ge grown on pSi will be uncovered.

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Capítulos de livros sobre o assunto "Germanium poreux"

Armatas, Gerasimos S., e Mercouri G. Kanatzidis. "Germanium-Based Porous Semiconductors from Molecular Zintl Anions". In Zintl Ions, 133–54. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/430_2010_22.

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Niwa, Miki, e Yuichi Murakami. "Function and characterization of CVD zeolites with controlled pore-opening sizes". In Chemistry and Technology of Silicon and Tin, 203–16. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780198555803.003.0014.

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Abstract Chemical vapour deposition (CVD) zeolites with precisely-controlled pore-opening sizes have been synthesized which show enhanced shapeselectivity and hence, increased efficiency in applications which include catalytic reactions and separations. The method involves the deposition of a silicon alkoxide on the external surface of the zeolites; the resulting layer of silica thus formed exerts a fine control on the pore-opening sizes. As examples of application, the selective cracking of octane isomers on mordenite, and the separation of oxygen and nitrogen on zeolite A, are described. The structure of the silica layer deposited on the external surface has been characterized by XPS, and indirectly by EXAFS by using a germanium alkoxide as a convenient probe in place of the silicon alkoxide. The germanium oxide layer formed on the zeolite was found to be very thin, but upon aggregation, the pore-controlling property of the layer was eliminated completely. These observations suggest that the silica layer on the CVD zeolite obtained under the controlled experimental conditions must also be very thin.

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Rogov, Alexey M., Viacheslav V. Vorobev, Vladimir I. Nuzhdin, Valery F. Valeev e Andrey L. Stepanov. "Porous silicon and germanium thin layers with silver nanoparticles". In Nanocomposites for Photonic and Electronic Applications, 167–92. Elsevier, 2020. http://dx.doi.org/10.1016/b978-0-12-818396-0.00007-8.

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Paillaud, J. L., Y. Lorgouilloux, B. Harbuzaru, P. Caullet, J. Patarin e N. Bats. "Structure orienting role of germanium in zeolite synthesis". In From Zeolites to Porous MOF Materials - The 40th Anniversary of International Zeolite Conference, Proceedings of the 15th International Zeolite Conference, 389–96. Elsevier, 2007. http://dx.doi.org/10.1016/s0167-2991(07)80865-2.

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Niwa, Miki, Carmela V. Hidalgo, Tadashi Hattori e Yuichi Murakami. "Germanium Methoxide: New Reagent for Controlling the Pore-Opening Size of Zeolite by CVD". In Studies in Surface Science and Catalysis, 297–304. Elsevier, 1986. http://dx.doi.org/10.1016/s0167-2991(09)60886-7.

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Trabalhos de conferências sobre o assunto "Germanium poreux"

Wietler, Tobias F., Eddy P. Rugeramigabo, Eberhard Bugiel e Enrique Garralaga Rojas. "Relaxed Germanium on Porous Silicon Substrates". In 2012 International Silicon-Germanium Technology and Device Meeting (ISTDM). IEEE, 2012. http://dx.doi.org/10.1109/istdm.2012.6222502.

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Schreiber, Waldemar, Jens Ohlmann, Patrick Schygulla, Stefan Janz, Jinyoun Cho e Kristof Dessein. "III-V Epitaxy on Detachable Porous Germanium 4” Substrates". In 2023 IEEE 50th Photovoltaic Specialists Conference (PVSC). IEEE, 2023. http://dx.doi.org/10.1109/pvsc48320.2023.10359546.

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Kabashin, Andrei V., Vincent-Gabriel Pilon Marien, D. Q. Yang, F. Magny e Michel Meunier. "Porous nanostructured layers on germanium produced by laser optical breakdown processing". In High-Power Lasers and Applications, editado por Alberto Pique, Koji Sugioka, Peter R. Herman, Jim Fieret, Friedrich G. Bachmann, Jan J. Dubowski, Willem Hoving et al. SPIE, 2003. http://dx.doi.org/10.1117/12.478574.

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Daniel, Valentin, Thomas Bidaud, Jeremie Chretien, Abdelatif Jaouad, Jean-francois Lerat, Nicolas Paupy, Bouraoui Ilahi et al. "Characteristics of Detachable III-V Solar Cells Grown on Porous Germanium". In 2023 IEEE 50th Photovoltaic Specialists Conference (PVSC). IEEE, 2023. http://dx.doi.org/10.1109/pvsc48320.2023.10359809.

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Tsybeskov, L., K. L. Moore, S. P. Duttagupta, K. D. Hirschman, D. G. Hall e P. M. Fauchet. "Fabrication and Luminescence of Large Si Nanocrystals". In Chemistry and Physics of Small-Scale Structures. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/cps.1997.ctub.6.

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The photoluminescence (PL) in crystalline silicon (c-Si) has been investigated during the last decades. Recent interest has focused on the visible PL that is observed in Si nanoclusters and in porous Si (PSi), the infrared PL in silicon-germanium superlattices, and the subgap PL due to impurities in c-Si [1]. Band edge PL in bulk Si is inefficient and usually observed only at low temperatures because c-Si has an indirect bandgap. The electroluminescence (EL) is as inefficient as the photoluminescence (PL) and, in addition, the EL is quenched by an electric field E ≥ 104 V/cm due to field-induced dissociation of the exciton. In this work we report a significant increase of the Si band edge photoluminescence and electroluminescence and its unexpectedly weak temperature dependence in large Si nanocrystals produced by the recrystallization of oxidized porous Si.

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Daniel, Valentin, Jeremie Chretien, Gwenaelle Hamon, Mathieu De Lafontaine, Nicolas Paupy, Zakaria Oulad El Hmaidi, Bouraoui Ilahi, Tadeas Hanus, Maxime Darnon e Abderraouf Boucherif. "Micro-fabrication and transfer of a detachable Ge epitaxial layer grown on porous germanium". In 2022 IEEE 49th Photovoltaics Specialists Conference (PVSC). IEEE, 2022. http://dx.doi.org/10.1109/pvsc48317.2022.9938777.

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Tsybeskov, L., K. D. Hirschman, S. P. Duttagupta, D. G. Hall e P. M. Fauchet. "Fabrication and Characterization of Si Dots Prepared by Self-Organized Recrystallization". In Quantum Optoelectronics. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/qo.1997.qfc.4.

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The photoluminescence (PL) in crystalline silicon (c-Si) has been investigated during the last decades. Interest has focused on the visible PL that is observed in Si nanoclusters and in porous Si (PSi), the infrared PL in silicon-germanium superlattices, and the subgap PL due to impurities in c-Si [1]. Whereas strong room-temperature PL has been demonstrated in the visible with porous silicon, band edge PL in bulk Si is inefficient and usually observed only at low temperatures. The electroluminescence (EL) is as inefficient as the PL, and, in addition, the EL is quenched by an electric field E ≥ 104V/cm due to field-induced dissociation of the exciton [2]. A result of the indirect bandgap of Si, bandgap luminescence is extremely weakly reabsorbed by Si. It follows that the light generated, propagated, and detected at the Si bandgap would not disturb the Si microelectronic circuitry with which it shares a chip, a situation that is very desirable for systems applications.

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Rivera, Johan, e Ongi Englander. "Mechanical and Thermal Properties of Highly Organized Nanowire-Alumina Nanocomposites". In ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-38186.

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The use of porous anodic alumina allows for the fabrication of highly ordered unidirectional nanowire composites. Sol gel deposition was used in the successful fabrication of zirconia-alumina and zinc oxide-alumina nanocomposites. Silicon-alumina and germanium-alumina nanocomposites were fabricated via catalyst-assisted chemical vapor deposition. The mechanical and thermal properties of these alumina nanocomposites were investigated. The Vickers hardness of the different nanocomposites was established by means of microindentation. Vickers testing was performed at room temperature and after specified heat treatments. The high temperature treatments were performed in order to assess the effect of an annealing step on the properties of the nanocomposites. Thermal cycling experiments were performed to test the nanocomposites’ compatibility with recurring high temperature environments.

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Kallel, A., G. Roux, T. Derycke, C. L. Martin, M. Marinova e C. Cayron. "Microstructure and thermoelectric properties of bulk and porous n-type silicon-germanium alloy prepared by HUP". In 9TH EUROPEAN CONFERENCE ON THERMOELECTRICS: ECT2011. AIP, 2012. http://dx.doi.org/10.1063/1.4731583.

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Arvinte, Roxana, Samuel Cailleaux, Alex Brice Poungoue Mbeunmi, Alexandre Heintz, Richard Ares e Abderraouf Boucherif. "Epitaxial lift-off process for III-V solar cells by using porous germanium for substrate re-use". In 2020 IEEE 47th Photovoltaic Specialists Conference (PVSC). IEEE, 2020. http://dx.doi.org/10.1109/pvsc45281.2020.9301028.

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