Sökning: "phonon"
Visar resultat 21 - 25 av 174 avhandlingar innehållade ordet phonon.
21. Microscopic Mechanisms of the Formation, Relaxation and Recombination of Excitons in Two-Dimensional Semiconductors
Sammanfattning : Monolayers of Transition Metal Dichalcogenides (TMDs) present a giant leap forward towards the realization of semiconductor devices with atomic scale thickness. As a natural consequence of their two-dimensional character TMDs exhibit a reduced dielectric screening, leading to the formation of unusually stable excitons, i.e. LÄS MER
22. Monte Carlo simulation of electron transport in semiconducting zigzag carbon nanotubes
Sammanfattning : Since the advent of nanoscale material based electronic devices, there has been a considerable interest in exploring carbon nanotubes from fundamental science and technological perspectives. In carbon nanotubes, the atoms form a cylindrical structure with a diameter of the order 1nm. LÄS MER
23. Role of charge and spin fluctuations and their interplay in solids : A Green’s function approach
Sammanfattning : Due to the large number of electrons, solid state physics boils down to many-body approximations in which only selected types of collective excitations are taken into account, guided by the emergent properties of the material under study. In this thesis, the collective excitations of primary interest are electronic charge and spin fluctuations(plasmons and magnons) and nuclear charge fluctuations (phonons). LÄS MER
24. Microscopic Theory of Exciton Dynamics in Two-Dimensional Materials
Sammanfattning : Transition Metal Dichalcogenides (TMDs) present a giant leap forward towards the realization of nanometer-sized quantum devices. As a direct consequence of their truly two-dimensional character, TMDs exhibit a strong Coulomb-interaction, leading to the formation of stable electron-hole pairs, so-called excitons. LÄS MER
25. Photo-induced Structural Dynamics in Transition Metal Dichalcogenides
Sammanfattning : Ultrafast electron microscope (UEM), a combination of transmission electron microscopy and laser-based pump-probe techniques, facilitates ultrafast imaging, diffraction, and electron-spectroscopy with high spatial resolution. The unique advantages of UEM enable local ultrafast dynamic studies in materials, nano-system, and biology. LÄS MER