Sökning: "semiconductors"

Visar resultat 21 - 25 av 327 avhandlingar innehållade ordet semiconductors.

1. 21. Optical Studies of InAs Quantum Dots in III-V Semiconductors

   Författare :Lars Landin; Fasta tillståndets fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; quantum dots; III-V semiconductors; k.p calculations; photoluminescence; deep-level transient spectroscopy; photoconductivity; few particle effect; single dot spectroscopy; InAs InP; Semiconductory physics; Halvledarfysik; Fysicumarkivet A:2000:Landin; InAs GaAs;

   Sammanfattning : I this thesis, optical studies of InAs quantum dots (QDs) in GaAs and InP are presented. The electronic structure of these zero dimensional structures, grown in the Stranski-Krastanow growth mode, was studied by photoluminescence spectroscopy (PL), junction space-charge techniques (JSCT) and photoconductivity (PC) measurements. LÄS MER

3. 22. 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

4. 23. Extreme Implementations of Wide-Bandgap Semiconductors in Power Electronics

   Författare :Juan Colmenares; Hans-Peter Nee; Leon M. Tolbert; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Cryogenic; Gallium Nitride; Gate Driver; Harsh Environments; High Efficiency Converter; High Temperature; MOSFETs; Normally- ON JFETs; Reliability; Silicon Carbide; Wide-Band Gap Semiconductors; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : Wide-bandgap (WBG) semiconductor materials such as silicon carbide (SiC) and gallium-nitride (GaN) allow higher voltage ratings, lower on-state voltage drops, higher switching frequencies, and higher maximum temperatures. All these advantages make them an attractive choice when high-power density and high-efficiency converters are targeted. LÄS MER

5. 24. Spectroscopic studies of III-V semiconductors in two, one and zero dimensions

   Författare :Dan Hessman; Fasta tillståndets fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; InAs-InP; low-dimensional structures; quantum wells; quantum dots; quantum wires; k.p calculations; type-II; photoluminescence; V grooves; Stranski Krastanow; single dot spectroscopy; GaAs-InP; III-V semiconductors; Fysicumarkivet A:1996:Hessman; InAs-GaAs; GaInAs-InP; Halvledarfysik; InP-GaInP; Semiconductory physics;

   Sammanfattning : In this thesis, spectroscopic studies of quantum wells (QWs), quantum wires (QWRs) and quantum dots (QDs) in III-V semiconductors are presented. The electronic structure of these low-dimensional structures have been studied by absorption, photocurrent, electroreflectance, photoluminescence (PL), and photoluminescence excitation (PLE) spectroscopy. LÄS MER

7. 25. Calculations of defect related properties in semiconductors

   Författare :Sven Öberg; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Scientific Computing; Teknisk-vetenskapliga beräkningar;

   Sammanfattning : Many of the most important and useful properties of crystalline materials, such as mechanical strength and electrical resistance, are determined by the presence of lattice defects and impurities. Well known examples are dislocations which control plastic flow and make metals ductile, and dopant atoms which control the extrinsic conduction in semiconductors and insulators. LÄS MER