Sökning: "carrier dynamics"

Visar resultat 1 - 5 av 98 avhandlingar innehållade orden carrier dynamics.

1. 1. Spatiotemporal carrier dynamics in graphene

   Författare :Roland Jago; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; spatiotemporal dynamics; density matrix formalism; graphene; relaxation dynamics; carrier multiplication; Bloch equations; photoconduction effect; bolometric effect;

   Sammanfattning : Graphene as an atomically thin material exhibits remarkable optical and electronic properties that suggest its technological application in novel optoelectronic devices, such as graphene-based photodetectors and lasers. To understand the properties of such devices on a microscopic level, we study the interplay of optical excitation, carrier-carrier, carrier-phonon, and carrierphoton scattering as well as diffusion processes. LÄS MER

3. 2. Electron-Lattice Dynamics in pi-Conjugated Systems

   Författare :Magnus Hultell (Andersson); Sven Stafström; Alexander Onipko; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Polaron dynamics; Exciton dynamics; pi-conjugated systems; Su-Schrieffer-Heeger SSH model; Adiabaticity; Charge carrier transport; Organic electronics.; Computational physics; Beräkningsfysik;

   Sammanfattning : In this thesis we explore in particular the dynamics of a special type of quasi-particle in pi-conjugated materials termed polaron, the origin of which is intimately related to the strong interactions between the electronic and the vibrational degrees of freedom within these systems. In order to conduct such studies with the particular focus of each appended paper, we simultaneously solve the time-dependent Schrödinger equation and the lattice equation of motion with a three-dimensional extension of the famous Su-Schrieffer-Heeger (SSH) model Hamiltonian. LÄS MER

4. 3. Carrier dynamics in semiconductor quantum dots

   Författare :Jörg Siegert; Ari Friberg; Jesper Mørk; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; quantum dots; photoluminescence; time-resolved; spectroscopy; semiconductor; Optics; Optik;

   Sammanfattning : This thesis presents results of time-resolved photoluminescence experiments conducted on several different self-assembled InGaAs/GaAs and InAs/GaAs semiconductor quantum dot (QD) structures. Depending on the application in mind, different structural, electronic or optical properties have a different weight of importance. LÄS MER

5. 4. Modal Dynamics of Vertical-Cavity Surface-Emitting Lasers

   Författare :Johan Gustavsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; transverse modes; noise; modeling; Semiconductor laser; dynamics; vertical-cavity surface-emitting laser;

   Sammanfattning : In this work, a comprehensive dynamic model has been developed for simulating a novel semiconductor laser type, referred to as the Vertical-Cavity Surface-Emitting Laser (VCSEL). The high-speed behavior was simulated and compared to experiments, where excellent agreement was found. LÄS MER

7. 5. Localization effects in ternary nitride semiconductors

   Författare :Vytautas Liuolia; Saulius Marcinkevicius; Toshiharu Saiki; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; AlGaN; InGaN; AlInN; LEDs; near-field microscopy; carrier dynamics; alloy fluctuations; carrier localization; built-in electric field; nonpolar planes; polarized luminescence;

   Sammanfattning : InGaN based blue and near-ultraviolet light emitting diodes and laser diodes have been successfully commercialized for many applications such as general lighting, display backlighting and high density optical storage devices. Despite having a comparably high defect density, these devices are known for their efficient operation, which is attributed to localization in potential fluctuations preventing carriers from reaching the centers of nonradiative recombination. LÄS MER