Semiconductor Structures
Mostrando 13-24 de 58 artigos, teses e dissertações.
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13. Filtros acústicos em cristais fonônicos
In this work, we have studied the acoustic phonon wave propagation within the periodic and quasiperiodic superlattices of Fibonacci type. These structures are formed by phononic crystals, whose periodicity allows the raise of regions known as stop bands, which prevent the phonon propagation throughout the structure for specific frequency values. This p
Publicado em: 2009
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14. SYNTHESIS METHODOLOGY FOR SIMPLIFIED ZVT TOPOLOGIES APPLIED TO BIDIRECTIONAL PWM POLES / METODOLOGIA DE SÍNTESE DE TOPOLOGIAS ZVT SIMPLIFICADAS APLICADAS A PÓLOS PWM BIDIRECIONAIS
Among the soft-switching techniques, the zero-voltage-transition (ZVT) technique has been accepted well by the industry due its attractive characteristics, such as simplicity, low losses in the auxiliary commutation circuit (ACC), operation with soft-switching for a wide load range, and closest operation to the PWM converter counterpart. In three-phase volta
Publicado em: 2009
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15. Propriedades opticas de nanofios de InP / Optical properties of InP nanowires
Optical properties of InP nanowires grown by Vapor-Liquid-Solid (VLS) method in a Chemical Beam Epitaxy system were investigated by using micro-photoluminescence spectroscopy varying experimental parameters such as excitation power, emitted signal polarization and sample temperature. Due to polytypism (InP in cubic, zincblende (ZB), and hexagonal, wurtzite (
Publicado em: 2009
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16. Caracterización eléctrica de películas delgadas de Al2O3 depositadas sobre GaAs por la técnica de rocío pirolítico
Electrical characteristics of thin films of aluminum oxide prepared by spray pyrolysis were studied. The films were prepared from solution onto single crystal GaAs (100) substrates at temperatures from 300°C to 600°C. The electrical characteristics of these films as a function of the substrate temperature were determined from the capacitance and current ve
Matéria (Rio de Janeiro). Publicado em: 2008-03
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17. Aplicação de computação em grade a simulações computacionais de estruturas semicondutoras / Applying grid computing on computational simulations of semiconductor structures
Neste trabalho foi avaliada a utilização da grid computing em aspectos importantes para simulações em Física Computacional. Em particular, para aplicações de diagonalização de matrizes de grande porte. O projeto de código aberto Globus Toolkit foi utilizado para comparar o desempenho da biblioteca paralela de álgebra linear ScaLAPACK em duas vers�
Publicado em: 2008
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18. Isolantes de porta com altas constantes dieletricas (High K) para tecnologia MOS / High K gate insulators for MOS technology
High k insulators for the next generation (sub-32 nm CMOS (complementary metaloxide-semiconductor) technology), such as titanium oxide (TiOx), titanium oxynitride (TiOxNy), titanium-aluminum oxynitride (AlxTiwOyNz), titanium-aluminum nitride (AlxTiwNz) and titanium-aluminum oxide (AlxTiwOy), have been obtained by Ti or Ti/Al e-beam evaporation, with addition
Publicado em: 2008
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19. Magneto-tunelamento ressonante em super-redes de GaAs/AsGaAs
In this thesis we present three works in weakly coupled semiconductor superlattices of GaAs/AlGaAs. In the first work we present an investigation of the electric field domain configuration in the sequential tunneling regime in weakly coupled superlattices in the presence of a magnetic field applied parallel to the quantum well layers. We show that, for an ap
Publicado em: 2008
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20. Nanocomposites and nanostructures of II-VI and IV-VI semiconductors / Nanocompositos e nanoestruturas de semicondutores das familias II-VI e IV-VI
The development of nanostructures and their applications constitute one of the most exciting scientific areas. A great number of studies in this area concern the preparation methods. Generally, they are classified in physical and chemical methods. The former class is based on molecular beam and lithography techniques, while the latter involves chemical react
Publicado em: 2007
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21. Desenvolvimento de processos de deposição de filmes filmes sobre substratos polimericos fotopolimerizdos / Development of process of deposition of thin films on photopolymerization polymeric substrats
A new era has begun all around the world. The quality of life and health depends more and more on the human capacity of resolving problems that are becoming longer and more complex day by day. As communication and globalization advance, time becomes scarcer and more precious. The semiconductor materials which are used to activate the logical functions, the h
Publicado em: 2007
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22. New physical interpretation of thermoelectric cooling in semiconductor structures
Nontraditional approach to explain the thermoelectric cooling is suggested . It is based on the Le Chatelier-Braun thermodynamic principle. New effect of cooling and heating of junction of two materials (barrierless thermoelectric cooling) is theoretically predicted, and this effect is different from the Peltier effect (barrier thermoelectric cooling). The s
Brazilian Journal of Physics. Publicado em: 2006-09
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23. Growth of mercuric iodide crystals
Mercuric Iodide (HgI2) is a semiconductor candidate for the construction of X- and gamma-ray detectors for digital medical imaging due to its high atomic number (Z Hg = 80, Z I = 53). Also, HgI2 has a wide optical band-gap (2.13 eV) and high photon absorption coefficient for high-energy radiation. Different structures can lead to varying electrical and optic
Brazilian Journal of Physics. Publicado em: 2006-06
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24. Study of the viability of production of semiconductors devices based on silicon carbide films grown by PECVD. / Estudo da viabilidade de fabricação de dispositivos semicondutores baseados em filmes de carbeto de silício crescidos por PECVD.
In this work we studied the viability to build devices based on stoichiometric amorphous silicon carbide semiconductor films (a-Si0.5C0.5:H), obtained by plasma enhanced chemical vapor deposition technique. The project proposal involves the realization of a series of studies that evaluate the potentialities of the a-SiC:H for the fabrication of simple semico
Publicado em: 2006