Sökning: "Thermal Diode"

Visar resultat 6 - 10 av 44 avhandlingar innehållade orden Thermal Diode.

  1. 6. Studies of Light Emitting Devices Based on Er-doped Si and SiGe Layered Structures

    Författare :Chun-Xia Du; Fransesco Priolo; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; electroluminescence; diode; transistor; hot electron; recombination; excitation; de-excitation; Auger effect; molecular beam epitaxy; Er; Si; SiGe;

    Sammanfattning : Doping with rare earth element erbium (Er) in Si has recently attracted a lot of research interest due to potential applications in Si-based opto-electronics. By using molecular beam epitaxy (MBE), precipitate-free Er-doping in Si has been made together with other co-dopants, e.g., oxygen (0) and fluorine (F), up to a level ∼1020 cm-3. LÄS MER

  3. 7. Magnetic Refrigeration for Near Room-Temperature Applications

    Författare :Behzad A Monfared; Björn Palm; Joachim Claesson; Andrew Rowe; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Magnetic Refrigeration; Magnetic; Cooling; Magnetocaloric; Life Cycle Assessment; Modeling; Simulation; Optimization; Regeneration; Active Magnetic Regeneration; Bonded Regenerator; Heat Switch; Thermal Diode; Peltier; Solid-State; Prototype; Magnetisk Kylteknik; Magnetisk; Kylning; Magnetokalorisk; Livscykela-nalys; Modellering; Simulering; Optimering; Regenerering; Aktiv Mag-netisk Regenerering; Bunden Regenerator; Värmebrytare; Termodiod; Peltier; Solid-State; Prototyp; Energy Technology; Energiteknik;

    Sammanfattning : Refrigeration plays a crucial role in many different sectors and consumes about 17% of the electricity produced globally. This significant energy consumption implies large share of refrigeration in primary energy consumption and other environmental impacts. LÄS MER

  4. 8. Thermal properties of volume Bragg gratings and its implications on lasers

    Författare :Staffan Tjörnhammar; Fredrik Laurell; Valdas Pasiskevicius; Mohamed Bourennane; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Thermal effects; Volume Bragg Gratings; VBG; Lasers;

    Sammanfattning : This thesis contains the results of research on the spectral control of lasers, specifically, the thermal limitations of volume Bragg gratings (VBGs), employed as laser-cavity end mirrors. The investigations consisted of both experiments and numerical simulations. LÄS MER

  5. 9. Understanding the interactions between vibrational modes and excited state relaxation in garnet structured phosphors

    Författare :Yuan-Chih Lin; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; free electron laser; thermal quenching.; luminescence; garnet; vibrational spectroscopy; neutron scattering; phosphor; light emitting diode;

    Sammanfattning : This thesis concerns investigations of the local structural environments and vibrational dynamics of the three garnet type oxide phosphors Ce3+-doped Y3Al5O12 (YAG:Ce3+), Ca3Sc2Si3O12 (CSS:Ce3+), and Sr3Y2Ge3O12 (SYG:Ce3+), which show promising optical properties as luminescent materials used in solid state white lighting technologies. The study focuses on a comprehensive analysis of the nature of the long-range vibrations (phonons) in terms of local atomic and molecular motions of the garnet structure, as well as their dependence on the nature of the garnet chemical composition, Ce3+ concentration and temperature. LÄS MER

  7. 10. Dynamic local structural symmetries and luminescence properties of the yellow emitting phosphor Ce3+-doped Y3Al5O12

    Författare :Yuan-Chih Lin; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; free electron laser; neutron scattering; vibrational spectroscopy; phosphor; light emitting diode; luminescence; thermal quenching; garnet;

    Sammanfattning : This thesis centers on investigations of the local structure and vibrational properties of the oxide garnet Y3Al5O12 (YAG), which when substituted with a few percent of the activator ion Ce3+ to replace Y3+ (Y3−xCexAl5O12, YAG:Ce3+) is one of the most important phosphors for solid state lighting. The study builds on a comprehensive analysis of the nature of the phonons and localized vibrational modes in YAG:Ce3+ and how these depend on the Ce3+ concentration and temperature and how they affect key optical properties, such as the intensity and frequency of the emitted light. LÄS MER