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Visar resultat 1 - 5 av 8 avhandlingar som matchar ovanstående sökkriterier.

1. 1. Threshold and Temperature Characteristics of InGa(N)As-GaAs Multiple Quantum Well Lasers

   Författare :Göran Adolfsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; GaAs; Semiconductor lasers; molecular beam epitaxy; multiple quantum wells; characteristic temperature; temperature dependence; dilute nitrides; ambipolar diffusion; InGa N As;

   Sammanfattning : Semiconductor lasers emitting in the 1.3 μm regime are of interest for applications in access-networks like fiber-to-the-home and radio-over-fiber systems. Suchfiber optical networks are expected to replace the copper-based access-networks currently in use due to a continuously increasing demand on user bandwidth. LÄS MER

3. 2. Dilute Nitride Lasers and Spectrally Engineered Semiconductor Laser Resonators

   Författare :Göran Adolfsson; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; single mode laser; transfer matrix method; threshold current; InGaAs; GaAs; multiple quantum wells; dilute nitrides; two-color laser; GaInNAs; Semiconductor lasers; molecular beam epitaxy; characteristic temperature; temperature dependence; ambipolar diusion; Fabry-Perot resonator; spectral engineering;

   Sammanfattning : The first part of this thesis deals with long wavelength (1.2-1.3 um) InGaAs(N)multiple quantum-well (QW) lasers grown on GaAs, with the aim of understandingand improving their threshold and temperature characteristics. The epitaxialmaterial is grown by molecular beam epitaxy (MBE). LÄS MER

4. 3. Studies of Charge Transport Processes in Dye-sensitized Solar Cells

   Författare :Kristofer Fredin; Anders Hagfeldt; Mukundan Thelakkat; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; solar cell; mesoporous; dye-sensitized; model; simulation; electron transport; trap distribution; Physical chemistry; Fysikalisk kemi;

   Sammanfattning : Dye-sensitized solar cells (DSCs) have attained considerable attention during the last decade because of the potential of becoming a low cost alternative to silicon based solar cells. Although efficiencies exceeding 10% in full sunlight have been presented, major improvements of the system are however limited. LÄS MER

5. 4. Impact of carrier localization on recombination in InGaN quantum wells with nonbasal crystallographic orientations

   Författare :Ruslan Ivanov; Saulius Marcinkevičius; Nicolas Grandjean; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; InGaN; quantum well; semipolar; nonpolar; near-field microscopy; carrier localization; carrier transport; optical polarization; Fysik; Physics;

   Sammanfattning : The modern InGaN technology demonstrates high efficiencies only in the blue spectral region and low current operation modes. The growth of InGaN quantum wells (QWs) on nonbasal crystallographic planes (NBP) has potential to deliver high-power blue and green light emitting diodes and lasers. LÄS MER

7. 5. Optical studies of carrier transport and fundamental absorption in 4H-SiC and Si

   Författare :Paulius Grivickas; KTH; []
   Nyckelord :;

   Sammanfattning : The Fourier transient grating (FTG) technique and a novelspectroscopic technique, both based on free carrier absorption(FCA) probing, have been applied to study the carrierdiffusivity in 4H-SiC and the fundamental absorption edge in4H-SiC and Si, respectively. FTG is a unique technique capable of detecting diffusioncoefficient dependence over a broad injection interval rangingfrom minority carrier diffusion to the ambipolar case. LÄS MER