Search for dissertations about: "phonons"
Showing result 21 - 25 of 70 swedish dissertations containing the word phonons.
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21. Graphene field-effect transistors and devices for advanced high-frequency applications
Abstract : New device technologies and materials are continuously investigated, in order to increase the bandwidth of high-speed electronics, thereby extending data rate and range of applications. The 2D-material graphene, with its intrinsically extremely high charge carrier velocity, is considered as a promising new channel material for advanced high frequency field-effect transistors. READ MORE
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22. Studies of Phonons and Phase Transitions by Time-Resolved X-ray Diffraction
Abstract : When light is used to study structures, the wavelength limits the size of the details that can be resolved. Visible light can be used to investigate structures as small as a micrometre in size. To study smaller structures a shorter wavelength is required. READ MORE
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23. Measurements of phonons in aluminium and lead with a neutron crystal spectrometer
Abstract : .... READ MORE
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24. Picosecond X-ray Diffraction Studies of Bulk and Nanostructure Materials
Abstract : Fast phenomena occurring after laser excitation were studied using time-resolved X-ray diffraction (TXRD). In most experiments, a femtosecond laser pulse was used to excite the sample, and X-rays were used as a probe. READ MORE
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25. Dynamic local structural symmetries and luminescence properties of the yellow emitting phosphor Ce3+-doped Y3Al5O12
Abstract : 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. READ MORE