Sökning: "alloy fluctuations"

Visar resultat 1 - 5 av 11 avhandlingar innehållade orden alloy fluctuations.

1. 1. 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

3. 2. Optical properties and degradation of deep ultraviolet AIGaN-based light-emitting diodes

   Författare :Andrea Pinos; Saulius Marcinkevicius; Andreas Hangleiter; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; AIGaN; deep-UV LEDs; polarization fields; screening; exciton binding energy; alloy fluctuations; near-field microscopy; carrier dynamics; LED aging; Optics; Optik;

   Sammanfattning : .... LÄS MER

4. 3. Optical properties of GaN and InGaN studied by time- and spatially-resolved spectroscopy

   Författare :Tomas Uždavinys; Saulius Marcinkevičius; Audrius Alkauskas; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Gallium nitride; InGaN; near-field microscopy; photoexcited carrier dynamics; intervalley energy; Fe centers; In incorporation; Physics; Fysik;

   Sammanfattning : The past decade has seen rapid expansion in the use of group III-nitride based devices. White InGaN LEDs are substituting incandescent light bulbs, space satellite industry adopting ion-radiation-resistant GaN transistors, and AlGaN deep UV LEDs are increasingly being used for water disinfection and air purification. 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. A theoretical study of magnetism and its extension to finite temperatures in random alloys

   Författare :Fan Pan; Lars Bergqvist; Richard Evans; KTH; []
   Nyckelord :Fysik; Physics;

   Sammanfattning : This work presents new theoretical developments of atomistic spin simulations of magnetic materials at finite temperatures. Special focus is put on the description of longitudinal magnetic fluctuations and the application in random transition metal alloys. LÄS MER