Дисертації з теми "Si and Ge nanostructures"
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Gadea, Gerard. "Integration of Si/Si-Ge nanostructures in micro-thermoelectric generators." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/459243.
Повний текст джерелаLos materiales termoeléctricos permiten la conversión de calor a electricidad y viceversa. Esto permite explotar el efecto termoeléctrico en generadores termoeléctricos, capaces de extraer energía térmica de fuentes calientes y convertirla a electricidad útil. Estos generadores presentan grandes ventajas, como su falta de piezas móviles – y por ende necesidad de mantenimiento alguna – y su total escalabilidad, que permite cambiar su tamaño sin afectar su rendimiento. Esto los hace obvios candidatos para la alimentación y carga de dispositivos portátiles y situados lugares de difícil acceso. A pesar de ello, su uso no está muy extendido debido a que su relación eficiencia-coste es baja en comparación a otros métodos capaces de suplir las funciones de alimentación – como la sustitución periódica de baterías – o de conversión térmica-eléctrica – como las turbinas de vapor. Los materiales termoeléctricos suelen ser o eficientes y caros (como el Bi2Te3 usado en los módulos comerciales) o ineficientes y de bajo coste (como el silicio, barato por su abundancia ya que supone un 28% de la corteza terrestre). En este trabajo se han crecido nanostructuras de silicio y silicio-germano, con dimensiones en el orden de los 100 nm. Los nanomateriales presentan propiedades termoeléctricas mejoradas respecto a sus contrapartes macroscópicas. Gracias a la nanoestructuración pues, se ha abordado del problema de eficiencia-coste por dos vertientes: • En el caso del silicio – normalmente un mal termoeléctrico debido a su alta conductividad térmica – se ha habilitado su uso como termoeléctrico al crecerlo en forma de nanohilos cristalinos y nanotubos de silicio policristalino. • En el caso de silicio-germano – que ya es un buen termoeléctrico para uso en altas temperaturas – se ha aumentado su eficiencia aún más, creciéndolo en forma de nanohilos. Yendo más allá de la síntesis, los nanohilos de silicio/silicio-germano se han optimizado, caracterizado en integrado en gran número micro-generadores termoeléctricos de 1 mm2 de superficie, pensados para la alimentación de pequeños dispositivos y circuitos integrados. Respecto a los nanotubos de Si, estos se han obtenido en densas fibras macroscópicas aptas para su aplicación directa como generadores termoeléctricos de gran área. Cabe mencionar que ambos nanomateriales – así como los microgeneradores basados en nanohilos – fueron obtenidos mediante técnicas actualmente utilizadas para la fabricación de circuitos integrados, pensando en la escalabilidad del proceso para su aplicación. El trabajo presentado en esta tesis consiste en el crecimiento, optimización, estudio e integración de nanostructuras de Si/Si-Ge para su aplicación en generación termoeléctrica. En los Capítulos 1 y 2 se pone un marco a los materiales tratados y su aplicación y se describen los métodos utilizados, respectivamente. Los resultados se han dividido en cuatro capítulos. En los Capítulos 3, 4 y 5 se tratan los nanohilos abordando su crecimiento, caracterización y aplicación en microgeneradores, respectivamente. En el Capítulo 6 se tratan las fibras de nanotubos, integrando todo el estudio en el mismo capítulo. Finalmente en el Capítulo 7 se muestran las conclusiones, resumiendo los resultados e indicando la relevancia del trabajo.
Elfving, Anders. "Near-infrared photodetectors based on Si/SiGe nanostructures." Doctoral thesis, Linköping : Surface and Semiconductor Physics, Linköping University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5909.
Повний текст джерелаPascale, Alina Mihaela. "Evolution morphologique des nanostructures Si(1-x)Ge(x) pendant la croissance par EJM." Aix-Marseille 2, 2003. https://tel.archives-ouvertes.fr/tel-00504903.
Повний текст джерелаIn this work we studied the Ge dots self-organization on vicinal Si substrates nanostructured by using a two stages process which consists of: i) substrate natural self-structuration and ii) Ge dots preferential nucleation on the created patterns. After bibliographical recalls in the first three chapters, we present the theoretical and experimental results in the two last chapters. In particular, we have evidenced: a) an implicit inverse Ehrlich-Schwoebel pseudo-barrier at the origin of the kinetic instability which develops during the homoepitaxial growth Si/Si(001), with scaling exponents in good agreement with the theory and b) an important reduction of the elastic energy of a system including a Ge dot, a Ge wetting layer and a Si patterned substrate (where each pattern is represented by steps) when the pattern is constitued of three steps at least
Portavoce, Alain. "Mécanismes élémentaires de redistribution de l'antimoine au cours de la croissance d'hétérostructure Si/Si(1-x)Ge(x) : Diffusion, ségrégation, désorption et effet surfactant." Aix-Marseille 3, 2002. http://www.theses.fr/2002AIX30060.
Повний текст джерелаThe future SiGe structures for micro and nano-electronic impose a strict doping control and for some of them a 3D confinement. We have analysed the dopant (B, Sb) redistribution phenomena during the MBE growth of SiGe layers in epitaxy on Si: diffusion, segregation, desorption, surfactant effect. Our approach (layers under various states of stress) permits to separate the Ge concentration effect from the strain effect. Sb diffusion increases with Ge concentration and with biaxial compression, while the B diffusion follows the opposite behaviour. We show that these variations are in agreement with a mechanism using principally vacancies for Sb and interstitials for B. Surface segregation during growth follows the same variations as diffusion, showing the prevalence of kinetics. The control of the superficial Sb coverage allows either the growth of thicker flat Ge layers or to reduce the size and to increase the density of Ge islands
Moontragoon, Pairot. "Band structure calculation of Si-Ge-Sn binary and ternary alloys, nanostructures and devices." Thesis, University of Leeds, 2009. http://etheses.whiterose.ac.uk/5850/.
Повний текст джерелаRuh, Elisabeth Margrit. "Investigation of the local Ge concentration in Si/SiGe nanostructures by convergent-beam electron diffraction /." Zürich : ETH, 2008. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=17908.
Повний текст джерелаBohorquez, Ballen Jaime. "Thermal transport in low dimensional semiconductor nanostructures." OpenSIUC, 2014. https://opensiuc.lib.siu.edu/dissertations/798.
Повний текст джерелаKozlowski, Grzegorz [Verfasser], and Thomas [Akademischer Betreuer] Schröder. "On the compliant behaviour of free-standing Si nanostructures on Si(001) for Ge nanoheteroepitaxy / Grzegorz Kozlowski. Betreuer: Thomas Schröder." Cottbus : Universitätsbibliothek der BTU Cottbus, 2012. http://d-nb.info/1022561456/34.
Повний текст джерелаCariou, Romain. "Epitaxial growth of Si(Ge) materials on Si and GaAs by low temperature PECVD: towards tandem devices." Palaiseau, Ecole polytechnique, 2014. https://theses.hal.science/tel-01113794/document.
Повний текст джерелаThis thesis focuses on epitaxial growth of Si and SiGe at low temperature (200°C) by Plasma Enhanced Chemical Vapor Deposition (PECVD), and its application in thin film crystalline solar cells. Our goal is to gain insight into this unusual growth process, as well as to investigate the potential of such low temperaturedeposited material for single and multi-junction solar cells. First, we have proposed a one pump-down plasma process to clean out-of-the-box c-Si wafer surface and grow epitaxial layers of up to 8µm thick, without ultra-high vacuum, in a standard RF-PECVD reactor. By exploring the experimental parameters space, the link between layer quality and important physical variables, such as silane dilution, ion energy, or deposition pressure, has been confirmed. Both material and electrical properties were analyzed, and we found that epitaxial quality improves with film thickness. Furthermore, we could bring evidence of SiGe and Ge epitaxial growth under similar conditions. Then, with the whole process steps <200°C, we have achieved PIN heterojunction solar cells on highly doped substrates with 1-4µm epitaxial absorber, reaching 8. 8% efficiency (without light trapping) and 80. 5% FF. Replacing Si absorber by epitaxial Si0:73Ge0:27 resulted in 11% boost in Jsc. The use of an engineered wafer/epitaxial layer interface and stress enables easy lift-off: e. G. We successfully bonded 1. 5µm thick 10cm^2 epi-Si to glass. Additionally, we have considered the impact of photonic nanostructures on device properties. Together, the control of growth, transfer and advanced light trapping are paving the way toward highly efficient, ultrathin (<10µm) and low cost c-Si cells. Finally, in contrast with general trend of growing III-V semiconductors on Si, we have studied the hetero-epitaxial growth of Si on III-V. Good crystal quality was achieved by direct Si deposition on GaAs, thanks to reduced thermal load and suppressed polarity issues in this approach. Using MOCVD, we could build GaAs cells with 20% efficiency and III-V tunnel junctions reaching 55A/cm^2. Tunneling improvement upon H-plasma exposure was shown. Those results, combined with III-V layer lift-off, validate milestones toward high efficiency tandem AlGaAs(MOVD)/SiGe(PECVD) metamorphic solar cells
Lin, Zhen. "AFM electrical mode development for nanostructure semiconductor study : application on Ge / Si nanostructure." Lyon, INSA, 2010. http://theses.insa-lyon.fr/publication/2010ISAL0135/these.pdf.
Повний текст джерелаNowadays, the semiconductor technology is facing a great challenge to increase the device performance while reducing its dimension. This downscaling in microelectronics industry causes a drastic development of microscopy to reveal new physical characteristics at nanoscale. The understanding of these new properties in nanometer scale is of prime importance. In this work, the AFM fundamental working principle and some typical electric property characterization techniques in semiconductor industry were introduced. The electrical AFM modes including scanning capacitance microscopy (SCM) and spectroscopy (SCS), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM) were developed at room temperature to study the properties of the promising replacement of the conventional poly-silicon floating gate, Germanium nanocrystals local Ge/Si nanostructures, which were fabricated by dewetting process. SCM, SCS, EFM and KPFM were proved to be available methodologies for semiconductor nanostructures characterizations, especially the nanocrystal study in nanometer scale. These characterisation works with developed AFM electrical mode are of prime importance in developing electronic devices application, especially the memory transistors application using Ge/Si nanocrystal
Khovaylo, V., A. Usenko, M. Gorshenkov, and S. Kaloshkin. "Optimization of Ball-Milling Process for Preparation of Si-Ge Nanostructured Thermoelectric Materials." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35302.
Повний текст джерелаWang, Xiaowei. "Thermoelectric property studies on nanostructured N-type Si-Ge Bulk Materials." Thesis, Boston College, 2009. http://hdl.handle.net/2345/2504.
Повний текст джерелаSiGe alloys are the only proven thermoelectric materials in power generation devices operating above 600 °C and up to 1000 °C in heat conversion into electricity using a radioisotope as the heat source. In addition to radioisotope applications, SiGe thermoelectric materials have many other potential applications, for example, solar thermal to electricity energy conversion and waste heat recovery. However, traditional SiGe alloy material shows low ZT values of about 0.93 at 900 °C, thus, 8% is the highest device efficiency for commercial SiGe thermoelectric devices. Recently, many efforts have been made to enhance the dimensionless thermoelectric figure-of-merit (ZT) of SiGe alloys. Among them, the nano approach has been recognized as an effective mechanism to obtain thermoelectric materials with good performance. In this approach, dense bulk samples with random nanostructures with high interface densities are synthesized through ball milling and a direct current hot press, leading to an enhancement ZT through reduced phonon thermal conductivity. Such a practical technique produced samples of nanostructured p-type dense bulk bismuth antimony telluride with a peak ZT of 1.4 at 1000 °C from either alloy ingot or elemental chunks. However, the generality of this approach has not been demonstrated. Here, we applied the same technique in SiGe system in order to fabricate a nanostructured n-type SiGe alloy with enhanced thermoelectric properties. In this thesis, numerous nanostructured n-type SiGe alloy samples were successfully pressed. The structure of these nanostructured samples was investigated via XRD, EDS, and TEM. It has been confirmed that many nano grains exist in our nanostructured samples
Thesis (PhD) — Boston College, 2009
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Physics
Voronin, A. I., A. A. Usenko, A. V. Korotitsky, D. U. Karpenkov, O. N. Maradudina, and V. V. Khovaylo. "Thermoelectric Properties of Si-Ge Nanostructured Thermoelectric Materials Synthesized by Mechanical Alloying." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35515.
Повний текст джерелаMortada, Hussein. "Croissance et caractérisation de nanostructures de Ge et Si déposées sur des substrats d'oxyde cristallin à forte permittivité LaA1O3." Phd thesis, Université de Haute Alsace - Mulhouse, 2009. http://tel.archives-ouvertes.fr/tel-00584121.
Повний текст джерелаUsenko, A., V. V. Khovaylo, A. I. Voronin, A. V. Korotitsky, D. Yu Karpenkov, and O. N. Maradudina. "Study of Compacting Methods for Nanostructured Thermoelectric Materials Based on Si-Ge and Half -Heusler Alloys." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35514.
Повний текст джерелаDujardin, Romain. "Epitaxie par jets moléculaires de nanostructures isolées de germanium sur silicium." Phd thesis, Université Joseph Fourier (Grenoble), 2006. http://tel.archives-ouvertes.fr/tel-00133594.
Повний текст джерелаliaison résiduelle Ge-O à l'interface entre les boîtes et le Si d'encapsulation. La croissance d'îlots de Si par épitaxie latérale à travers la couche d'oxyde a permis de supprimer ces liaisons et d'obtenir une luminescence des boîtes de Ge dans l'infra rouge avec une très faible largeur de raie. Ce phénomène est attribué à une faible dispersion en taille des boites
de Ge élaborées sur ces ilots de Si. Le dernier volet de ces travaux a porté sur l'élaboration de nanofils de Si par la voie VLS et sur l'incorporation de couches fines de Ge dans ces nanofils. L'interdiffusion du silicium dans ces couches de Ge a été quantifié par diffraction anomale et la structure cristalline des fils a été étudiée par MET.
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.
Повний текст джерелаJoshi, Giri Raj. "Study of Thermoelectric Properties of Nanostructured P-Type Si-Ge, Bi-Te, Bi-Sb, and Half-Heusler Bulk Materials." Thesis, Boston College, 2010. http://hdl.handle.net/2345/2463.
Повний текст джерелаSilicon germanium alloys (SiGe) have long been used in thermoelectric modules for deep-space missions to convert radio-isotope heat into electricity. They also hold promise in terrestrial applications such as waste heat recovery. The performance of these materials depends on the dimensionless figure-of-merit ZT (= S2σ T/ κ), where S is the Seebeck coefficient, σ the electrical conductivity, κ the thermal conductivity, and T is the absolute temperature. Since 1960 efforts have been made to improve the ZT of SiGe alloys, with the peak ZT of n-type SiGe reaching 1 at 900 - 950 C. However, the ZT of p-type SiGe has remained low. Current space-flights run on p-type materials with a peak ZT ~ 0.5 and the best reported p-type material has a peak ZT of about 0.65. In recent years, many studies have shown a significant enhancement of ZT in other material systems by utilizing a nanostructuring approach to reduce the thermal conductivity by scattering phonons more effectively than electrons. Here we show, using a low-cost and mass-production ball milling and direct-current induced hot press compaction nanocomposite process, that a 50% improvement in the peak ZT, from 0.65 to 0.95 at 800 - 900C is achieved in p-type nanostructured SiGe bulk alloys. The ZT enhancement mainly comes from a large reduction in the thermal conductivity due to the increased phonon scattering at the grain boundaries and crystal defects formed by lattice distortion, with some contribution from the increased electron power factor at high temperatures. Moreover, nanocomposite approaches have been used to study the thermoelectric properties of other material systems such as bismuth telluride (Bi-Te), bismuth antimony (Bi-Sb), and half-Heusler phases. We observed a significant improvement in peak ZT of nanostructured p- and n-type half-Heusler compounds from 0.5 to 0.8 and 0.8 to 1.0 respectively. The ZT improvement is mainly due to the reduction of thermal conductivity. This nanostructure approach is applicable to many other thermoelectric materials that are useful for automotive, industrial waste heat recovery, space power generation, or solar power conversion applications
Thesis (PhD) — Boston College, 2010
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Physics
Poydenot, Valier. "BOÎTES ET FILS DE GE SUR SI(001) ORDONNÉS À LONGUE DISTANCE PAR DES RÉSEAUX DE DISLOCATIONS DE FLEXION." Phd thesis, Université Joseph Fourier (Grenoble), 2005. http://tel.archives-ouvertes.fr/tel-00134942.
Повний текст джерелаKallel, Houssem. "Étude des propriétés optiques de nanofils individuels de Si, de Ge, et d'alliages et hétérostructures SiGe pour le contrôle de l'absorption et de la diffusion de la lumière." Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2438/.
Повний текст джерелаIn this thesis is presented a study of the optical response of individual semiconductor nanowires in order to determine the key parameters controlling the interaction of light with a nanowire. The main objective is to enhance either the absorption efficiency for photovoltaic applications or the scattering efficiency for the control of light emission. In a first step, calculations of the optical response of single Si_{1-x}Ge_{x} nanowires performed using the analytical Mie theory, show that optical resonances occur in the solar sun wavelength range. Such resonances can be tuned by changing the nanowire diameter and Ge composition. The calculations are compared to light scattering experiments performed using dark field confocal optical microscopy on single nanowires of different diameter and Ge composition. In a second step, the theoretical study is extended to complex structures such as core-sheath Ge/Si structures to optimize the absorption efficiency compared to simple nanowires. At last, the nanowire-light emitter interaction is evidenced by the polarization dependent photoluminescence enhancement of a Si nanocrystal plane positioned in the near field of a Si nanowire, which one behaves as an optical antenna by analogy with plasmonic nanostructures. Furthermore, we show a correlation between the increase of the local electromagnetic field intensity, obtained by numerical simulations, and the Si nanocrystal photoluminescence enhancement
Luan, Hsin-Chiao 1969. "Ge photodetectors for Si microphotonics." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8782.
Повний текст джерелаIncludes bibliographical references (p. 143-157).
This thesis demonstrates the integration of pure Ge near-infrared photodetectors on Si. Ge epilayers were grown directly on Si by a two-step ultra-high-vacuum/chemical-vapor-deposition (UHV/CVD) process. This work conclusively proves that threading-dislocation densities in the Ge epilayers, measured both by plan-view transmission electron microscopy and etch-pit-density (EPD) counting, were reduced by cyclic thermal annealing. Additionally, Ge mesas with no threading dislocations as measured by EPD were also demonstrated. The removal of threading-dislocations can be attributed to the thermal stress induced dislocation glide and reactions. Using the annealed Ge epilayers grown on Si, p-i-n Ge photodetectors with maximum responsivities of 770 mA/W at 1.3 μm were fabricated. Finally, to allow the integration of Ge epilayers in Si microelectronic processing, the protection and passivation of Ge was investigated. The passivation was provided by the oxidation of Si epilayers grown on Ge. Capacitance-voltage characteristics of metal-oxide-semiconductor devices demonstrated the high quality of the passivation with the measured interface state density of 4 x 1011 cm-2eV- 1.
by Hsin-Chiao Luan.
Ph.D.
Aubel, Dominique. "Apport des techniques de photoémission à la connaissance des hétérostructures Ge/Si(001), Si/Ge(001), Si1-xGex/Si(001) et Si1-xGex/Ge(001)." Mulhouse, 1995. http://www.theses.fr/1995MULH0412.
Повний текст джерелаYang, Chih Meng Atwater Harry Albert. "Manipulation of Si and Ge crystallization /." Diss., Pasadena, Calif. : California Institute of Technology, 1997. http://resolver.caltech.edu/CaltechETD:etd-01162008-112621.
Повний текст джерелаДубина, В. М. "Термодинамічні властивості розплавів потрійних систем Ge(Si)-Mn-AI, Ge(Si)-Ga-Y та Al-Ga-Y". Дис. канд. хім. наук, КНУТШ, 2004.
Знайти повний текст джерелаTeichmann, Marc. "Musterbildung auf Si- und Ge-Oberflächen durch niederenergetische Ionenstrahlerosion: Musterbildung auf Si- und Ge-Oberflächen durch niederenergetische Ionenstrahlerosion." Doctoral thesis, Leibniz-Institut für Oberflächenmodifizierung e. V, 2014. https://ul.qucosa.de/id/qucosa%3A13404.
Повний текст джерелаFerrando, Villalba Pablo. "Thermal characterization of Si-based nanostructures." Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/399339.
Повний текст джерелаThermoelectricity is a promising technology for scavenging energy from environmental temperature differences. The development of materials that transform heat into electricity in a more efficient way making use of this principle is necessary for opening new application niches. Nanostructuring a material has been demonstrated to increase the thermoelectric figure of merit of crystalline materials via a thermal conductivity reduction driven by enhanced phonon scattering. This thesis is committed to give a better insight into the processes that affect thermal transport in potential Si-based nanomaterials for thermoelectric generation. In Chapter 1, a general introduction exposes the need for reducing fossil fuel consumption and generally using renewable energies. Also, the benefit of tuning the thermal conductivity of materials for thermal management applications is discussed. Chapter 2 provides an overview of the theory behind thermal transport. First, the heat equation is derived from the classical irreversible thermodynamics framework. Then, phonons are introduced as heat carrying quasiparticles. The application of the Boltzmann Transport Equation to both phonons and electrons allows understanding the effect of different scattering mechanisms on the thermoelectric properties of materials. Finally, several strategies for enhancing the figure of merit of materials are reviewed. In Chapter 3, the necessary tools for measuring the thermal conductivity of nanomaterials are developed. Two cryostats are set up along with the temperature control systems that allow measuring at stable temperatures. Later, three sensors are developed for measuring the thermal conductivity of different materials. First, suspended structures intended for measuring the in-plane thermal conductivity of suspended membranes and nanowires are fabricated, and the errors and uncertainties produced in such measurements are characterized. Second, the 3ω method is introduced, allowing the measurement of the out-of-plane thermal conductivity in thin films. The emergence of the 3ω voltage is demonstrated, and the relation between this voltage and the thermal conductivity of the substrate and the thin-film is found. Finally, a sensor for the 3ω-Völklein method is developed, which allows characterizing the in-plane thermal conductivity of thin-films during the layer growth. In Chapter 4, the thermal conductivity of suspended Si membranes is measured, finding the expected reduction in thermal conductivity due to phonon surface scattering, as well as confinement effects in the 17.5 nm thick membrane. Moreover, the nanopatterning of these Si membranes with focused ion beam (FIB) is optimized through a systematic study of its amorphization finding an optimal spatial resolution of 200 nm when using 50 μC/cm2. In Chapter 5, the thermal conductivity of porous Si nanowires is studied for wires with different porosity, length and diameters, showing an unexpected dependence on its diameter that suggests that the wire core is generally less porous than the shell. The structural Si thermal conductivity is found to be one fiftieth of that of the bulk, promising a good thermoelectric figure of merit. In Chapter 6, the thermal conductivity of a novel SiGe graded superlattice is measured, showing a considerable reduction in its thermal conductivity, even below the thin-film alloy limit. The measurement of the thickest superlattice confirms the absence of coherent phonon effects. In Chapter 7, the thermal conductance of a suspended SiNx membrane is measured with a high precision while depositing on it organic (TPD) and metallic (Indium) materials. The results show an initial conductance reduction that cannot be explained with the Fourier law. This reduction is found to be related to an increased diffusive boundary scattering, which could be easily extrapolated to other thermoelectric nanomaterials, reducing their thermal conductivity. Also, the growth dynamics of both materials are characterized through their signal in the conductance.
White, Julian Darryn. "Phonons in (Si)_m/(Ge)_n superlattices." Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239759.
Повний текст джерелаCamacho-Aguilera, Rodolfo Ernesto. "Ge-on-Si laser for silicon photonics." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82173.
Повний текст джерелаThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (p. 253-263).
Ge-on-Si devices are explored for photonic integration. Importance of Ge in photonics has grown and through techniques developed in our group we demonstrated low density of dislocations (<1x109cm-2) and point defects Ge growth for photonic devices. The focus of this document will be exclusively on Ge light emitters. Ge is an indirect band gap material that has shown the ability to act like a pseudo direct band gap material. Through the use of tensile strain and heavy doping, Ge exhibits properties thought exclusive of direct band gap materials. Dependence on temperature suggests strong interaction between indirect bands, [Delta] and L, and the direct band gap at [Gamma]. The behavior is justified through increase in photoluminescence on Ge. The range of efficient emission is to 120° with the first band interaction, and above 400° on the second band interaction. Low defect concentration in Ge is achieved through chemical vapor deposition at high vacuum (~1x10-8 mbar) in a two-step process. The high temperature growth and low concentration of particles permits epitaxial growth with low defect concentration. Chemical selectivity forbids Ge growth on oxide. Oxide trenches permit the growth on Si for a variety of shapes, without detrimentally affecting the strain of the Ge devices. Dopant concentration above intrinsic growth concentration, ~1x1019cm-3 phosphorus, have been achieved through a series of methods non-CMOS, spin-on dopant; and CMOS, implantation and delta doping. All the techniques explored use enhanced dopant diffusion observed in Ge under heavy n-type doping. A dopant source, or well, is used to distribute the dopants in the Ge without increasing the defect concentration. The approach lead to the development of electrically injected devices, LEDs and LDs. Ge pnn double heterostructure diodes were made under low, ~1x1018cm-3, and heavy n-type doping, >1x1019cm-3. Both devices showed improved performance compared to pin Ge LED. Furthermore, heavy doped Ge diodes exhibit evidence of bleaching or transparency. The techniques described permitted the development of Ge-on-Si laser with a concentration ~1-2x1019cm-3. It is the first demonstration of a Ge laser optically pumped working under the direct band gap assumption like other semiconductors. It represents the evidence of carrier inversion on an indirect band gap semiconductor. With 50cm-1 gain, the material shows Fabry-Perot cavity behavior. Finally, we demonstrated a fully functioning laser diode monolithically integrated on Si. Ge pnn lasers were made exhibiting a gain >1000cm-1 and exhibiting a spectrum range of over 200nm, making Ge the ideal candidate for Si photonics.
by Rodolfo E. Camacho-Aguilera.
Ph.D.
Okyay, Ali Kemal. "Si-Ge photodetection technologies for integrated optoelectronics /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Повний текст джерелаVan, Sothachett. "Elaboration des interfaces Ge/Si(111) et Ge/Si(100) par UHV-CTLCVD : caractérisation par ARUPS, XPD et LEED." Mulhouse, 1994. http://www.theses.fr/1994MULH0322.
Повний текст джерелаGuangnan, Zhou. "Impact of doping on epitaxial Ge thin film quality and Si-Ge interdiffusion." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62996.
Повний текст джерелаApplied Science, Faculty of
Materials Engineering, Department of
Graduate
Fink, Andreas. "Organische Moleküle auf Halbleitern: Adsorption und elektronische Struktur ungesättigter Kohlenwasserstoffe auf Si(100)-, Ge/Si(100)- und Ge(100)-Oberflächen." [S.l. : s.n.], 2001. http://deposit.ddb.de/cgi-bin/dokserv?idn=96278673X.
Повний текст джерелаTolstoguzov, A., B. Ber, P. Chapon, and M. N. Drozdov. "Depth Profiling of Multilayer Mo/Si Nanostructures." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35262.
Повний текст джерелаPiels, Molly. "Si/Ge photodiodes for coherent and analog communication." Thesis, University of California, Santa Barbara, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3612014.
Повний текст джерелаHigh-speed photodiodes have diverse applications in wireless and fiber communications. They can be used as output stages for antenna systems as well as receivers for fiber optic networks. Silicon is an attractive substrate material for photonic components for a number of reasons. Low cost manufacturing in CMOS fabrication facilities, low material loss at telecommunications wavelengths, and relatively simple co-packaging with electronics are all driving interest in silicon photonic devices. Since silicon does not absorb light at telecommunications wavelengths, photodetector fabrication requires the integration of either III-V materials or germanium. Recent work on germanium photodetectors has focused on low-capacitance devices suitable for integration with silicon electronics. These devices have excellent bandwidth and efficiency, but have not been designed for the levels of photocurrent required by coherent and analog systems. This thesis explores the design, fabrication, and measurement of photodetectors fabricated on silicon with germanium absorbing regions for high speed and high power performance.
There are numerous design trade-offs between speed, efficiency, and output power. Designing for high bandwidth favors small devices for low capacitance. Small devices require abrupt absorption profiles for good efficiency, but design for high output power favors large devices with dilute absorption. The absorption profile can be controlled by the absorber layer thickness, but this will also affect the bandwidth and power handling. This work quantifies the trade-offs between high speed, high efficiency, and high power design. Intrinsic region thickness and absorption profile are identified as the most important design variables. For PIN structures, the absorption profile and intrinsic region thickness are both functions of the Ge thickness, but in uni-traveling carrier (UTC) structures the absorption profile and intrinsic region can be designed independently. This allows optimization of the absorption profile independently from the RC-limited frequency response and compression current and ultimately enables larger saturation current-bandwidth products. This thesis includes the first theory, fabrication, and measurement of a uni-traveling carrier photodiode on the Si/Ge platform. Key contributions include an accurate nonlinear device model and a complete set of processes and design rules for fabricating Ge devices in the UCSB nanofab. The UTC structure is shown to be useful in extending the bandwidth and power handling capabilities of waveguide-integrated photodiodes, especially at high frequencies.
Živanović, Goran. "Design considerations for Ge-on-Si waveguide photodetector." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/91083.
Повний текст джерела45
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 108-114).
In integrated photonic circuits photodetector is one of key components, modern applications require that photodetector has a high 3 dB bandwidth. The ultimate limit for the response time for conventional photodetectors (like vertically illuminated photodiode, Schotky photodiode, MSM photodetector etc.) is given by the transit time of the photogenerated electron-hole pairs, it can not be minimised by decreasing the thickness of the depletion region without reducing quantum efficiency (i.e. the fraction of the incident light that is absorbed). Waveguide photodetectors have been developed to overcome this trade-off. In the waveguide photodetector light propagates in a direction that is parallel to the junction interfaces and is perpendicular to the drift of the generated electron-hole pairs. This geometry decouples absorption length from the drift length. Therefore the waveguide photodetector can have both a very thin active region for short transit time and a long absorption length for a high quantum efficiency. In this thesis , I designed germanium on silicon photodetector. The main designing tool was full vectorial 3D Finite Difference Time Domain (FDTD) simulator. Bandwidth-efficiency product was used as the main figure of merit. The input is silicon rib waveguide, which is optimised to maximize transmitted power. For optimal dimensions of the device calculated responsivity is 0.94 A/W, efficiency is 83 %, bandwidth is 64 GHz and bandwidth x efficiency product is 53 GHz.
by Goran Živanović.
S.M.
Silva, Marcos Antonio Araujo. "Espalhamento Raman em heteroestruturas semicondutoras de Si/Ge." [s.n.], 1995. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277744.
Повний текст джерелаTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
Made available in DSpace on 2018-07-20T17:20:50Z (GMT). No. of bitstreams: 1 Silva_MarcosAntonioAraujo_D.pdf: 2541195 bytes, checksum: 3f6719299d5a08183c7b43e174b72215 (MD5) Previous issue date: 1995
Resumo: Nós utilizamos espectroscopia Raman para estudar a dinâmica de rede de heteroestruturas semicondutoras de Si/Ge, tanto experimental quanto teoricamente. Foi feito um estudo de uma ampla região espectral, (de ~ 2 cm-1 até 600 cm-1), que inclui fônons acústicos dobrados, fônons de interface, e fônons ópticos confinados. Nós utilizamos vários sistemas experimentais: um sistema usual, um sistema de alta resolução, e um sistema de micro-Raman. Pelo lado teórico, nós aplicamos o modelo da cadeia linear unidimensional, com interação de até segundos vizinhos, e usamos o modelo bond-polarizability para simular os espectros Raman. Uma análise fenomenológica nos permitiu verificar a presença de rugosidade de larga escala (terraços) nas interfaces de nossas amostras. Medidas de espalhamento Raman ressonante também foram feitas para os fônons ópticos de nossas microestruturas. Uma análise quantitativa da seção de choque Raman do pico originado nas vibrações confinadas Ge-Ge, permitiu-nos acompanhar as transições ópticas dos éxcitons confinados em cada terraço. Esta análise favorece nossas interpretações anteriores a respeito desta transição, que a relaciona a transições do tipo E1 do Ge bulk
Abstract: We have used Raman spectroscopy to study the lattice dynamics of Ge/Si semiconductor heterostructures, both experimentally and theoretically. The study was performed in a broad spectral range (from 2 cm-1 up to 600 cm-1), which includes the acoustical folded phonons, interfaces phonons, and confined optical phonons. We have used several experimental systems: a standard, a high resolution, and a micro-Raman setup. Theoretically, we have applied a one-dimensional linear-chain model with second-neighbor interactions to obtain the vibrational modes and a bond-polarizability model to simulate the Raman spectra. A phenomenological analysis allows us to verify the presence of large scale roughness (terraces) in the interfaces of our samples. Resonant Raman measurements were also performed for the optical phonons of our microstructures. Quantitative analysis of the resonant-Raman cross-section of the peak originating in Ge-Ge confined vibrations allows us to single out optical transitions of excitons confined within each terrace. This analysis favours our previous interpretation of this transition, which relates it to the E1-transitions of bulk Ge
Doutorado
Física
Doutor em Ciências
Малецький, М. А. "Фотоелектричні властивості тонких напівпровідникових плівок Ge та Si". Master's thesis, Сумський державний університет, 2020. https://essuir.sumdu.edu.ua/handle/123456789/82012.
Повний текст джерелаGan, Wei. "Precipitation and strengthening in AL-GE-SI alloys." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1135275701.
Повний текст джерелаPulido, Junquera Maria Angeles. "Estudio computacional de las Si, Ge, F-zeolitas." Doctoral thesis, Universitat Politècnica de València, 2008. http://hdl.handle.net/10251/1867.
Повний текст джерелаPulido Junquera, MA. (2006). Estudio computacional de las Si, Ge, F-zeolitas [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1867
Palancia
El, Kadib Abdelkrim. "Métallation (Si, Ge) des esters méthyliques d'acides gras." Toulouse 3, 2004. http://www.theses.fr/2004TOU30185.
Повний текст джерелаThe present work describes the metalation (Si, Ge) of fatty acid methyl esters (FAME) and raw fish oil. In the first time, the hydrometalation of FAME has been carried out. The free-radical initiation sequence led to metal embedded products with a better selectivity. The a-silylation of the ester functional group of FAME was detailed, whether through silyltriflates or from the respective enolates of the FAME. For each procedure, the optimization of the operational conditions drove to obtaining exclusive of C-silylated products. The fourth chapter detailed obtaining biosilicones by polycondensation of the silylated FAME. Molecular modelling revealed an almost perfect "bio-masking" of the siloxanes by the FAME, thus showing the high interest that of these polymers can present concerning their growth regarding biocompatibility. In the last chapter a particularly interesting application of the silylated precursors has been developed: the ability of self-reorganisation of these molecular units allowed producing silica-based nanomaterials
Robinson, Dirk J. "High speed data converter circuits in SI-GE." Pullman, Wash. : Washington State University, 2008. http://www.dissertations.wsu.edu/Dissertations/Fall2008/d_robinson_121008.pdf.
Повний текст джерелаTitle from PDF title page (viewed on Jan. 15, 2009). "School of Electrical Engineering and Computer Science." Includes bibliographical references (p. 60-61).
Sivadasan, Vineet. "Strain relaxation study of Si1-xGex & Ge buffer layers on Si(001) and InSb on Ge/Si(001) virtual substrates." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/89938/.
Повний текст джерелаGoh, Johnathan Jian Ming. "Commercialization potential of compositionally graded Ge - Si₁₋x̳Gex̳ - Si substrates for solar applications." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38550.
Повний текст джерелаIn title on t.p., double-underscored "x" appears as subscript.
Includes bibliographical references.
This project considers the potential of Ge - Si₁₋x̳Gex̳ - Si substrates for solar applications. The use of compositionally graded substrates to achieve heterointegration across different materials platforms such as Si, Ge and GaAs has proven successful and dual junction solar cells have been fabricated on such substrates. The potential for graded substrates in the solar market is discussed considering the current technology, market players and worldwide renewable energy policies. A cost model is also developed and analyzed in the course of writing to assess the feasibility of this commercial enterprise. The result of these analyses highlights the technical and commercial viability of graded substrates in the solar market.
by Johnathan Jian Ming Goh.
M.Eng.
Nguyen-Duc, Trung-Kien. "Croissance épitaxiale et propriétés optiques des îlots auto-assemblés Ge/Si et des super-réseaux de courte période Ge(m)Si(n)." Aix-Marseille 2, 2005. http://theses.univ-amu.fr.lama.univ-amu.fr/2005AIX22086.pdf.
Повний текст джерелаMenard, Stéphane. "Propriétés optiques et électriques des nanostructures Si/CaF2." Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10235.
Повний текст джерелаWigblad, Dan. "Structural and optical characterization of Si/Ge quantum dots." Thesis, Linköping University, The Department of Physics, Chemistry and Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-11672.
Повний текст джерелаIn this study silicon-germanium quantum dots grown on silicon have been investigated. The aim of the work was to find quantum dots suitable for use as a thermistor material. The quantum dots were produced at KTH, Stockholm, using a RPCVD reactor that is designed for industrial production.
The techniques used to study the quantum dots were: HRSEM, AFM, HRXRD, FTPL, and Raman spectroscopy. Quantum dots have been produced in single and multilayer structures.
As a result of this work a multilayer structure with 5 layers of quantum dots was produced with a theoretical temperature coefficient of resistance of 4.1 %/K.
Wietler, Tobias [Verfasser]. "Surfactant-modifizierte Epitaxie für Ge/Si-Heterobauelemente / Tobias Wietler." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover, 2010. http://d-nb.info/1010987275/34.
Повний текст джерелаTeichmann, Marc. "Musterbildung auf Si- und Ge-Oberflächen durch niederenergetische Ionenstrahlerosion." Doctoral thesis, Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-175110.
Повний текст джерелаKim, Meekyung Ph D. Massachusetts Institute of Technology. "Limited-area growth of Ge and SiGe on Si." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/62743.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (p. 147-159).
The goal of this thesis is to develop and understand processing conditions that improve the surface morphology and reduce the dislocation density in limited-area heteroepitaxy of Ge and SiGe on Si (100) substrates. Low pressure chemical vapor deposition was investigated for two limiting cases of strain states: thin, strained, high Ge content SiGe films for transistor applications, and thick, relaxed Ge films, for potential optoelectronic applications. Selective epitaxial growth of thin, high Ge-content, strained SiGe on oxide-patterned silicon was studied, specifically the effect of growth area on the critical thickness. The critical thickness of Sio.33Geo.67 formed by selective epitaxial growth in areas of 2.3 x 2.3 [mu]m was found to be 8.5 nm, which is an increase of 2x compared to the critical thickness observed for growth in large areas (i.e. for non-selective epitaxy). The sources of misfit dislocation nucleation in selective growth were analyzed, and misfit generation from the SiGe pattern edges, due to effects such as local strain concentration, Si surface shape near the oxide boundary, and preferential SiGe growth near the pattern edge were investigated. Thin, smooth Ge-on-Si films were developed and the effect of growth conditions on film morphology was examined to find an optimum temperature and pressure for smooth film surface (365 °C and 60 torr). A period of delayed epitaxial growth, or "incubation time" was observed, and a Si surface treatment technique, consisting of a short SiGe pulse, with negligible SiGe thickness, was employed to realize uniform Ge films with low surface roughness (RMS<0.3 nm) and reduced incubation time (<20 seconds). For selective growth of relaxed, thick Ge, approximately 1 pm-thick Ge films were grown in exposed Si regions on oxide-patterned wafers, and germanium selectivity, faceting, surface roughness and threading dislocation density were studied as functions of growth and processing conditions. The optimal growth condition for relaxed Ge selective epitaxial growth was found (750 °C and 10 torr, with 100 sccms of GeH4 and 10 slpm H2 flow), and the effect of thermal annealing, Ge film thickness, and growth area on the threading dislocation density was also studied.
by Meekyung Kim.
Ph.D.
Paul, Neelima [Verfasser]. "Bi surfactant mediated growth for fabrication of Si/Ge nanostructures and investigation of Si/Ge intermixing by STM / vorgelegt von Neelima Paul." 2007. http://d-nb.info/987093444/34.
Повний текст джерела