Sökning: "Low-dimensional structures"

Visar resultat 1 - 5 av 61 avhandlingar innehållade orden Low-dimensional structures.

1. 1. Electron Transport in Low Dimensional Systems

   Författare :Peter Ramvall; Fasta tillståndets fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; high mobility; low-dimensional structures; III-V semiconductors; quantum wells; heterojunctions; quantum Hall effect; edge channels; Shubnikov-de Haas effect; alloy-disorder scattering; Y-branch switch; two dimensional electron gas; Fysik; Fysicumarkivet A:1996:Ramvall; Physics; spin splitting; mag;

   Sammanfattning : This thesis consists of experimental studies of transport properties in high mobility two dimensional electron gases (2DEGs). Two material systems are used, an AlGaAs/GaAs heterojunction and a GaInAs/InP quantum well. LÄS MER

3. 2. Optical Properties of Low Dimensional Semiconductor Materials

   Författare :Tiantian Han; Ying Fu; Per-Olof Holtz; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Semiconductor; Low dimensional; optics; Physics; Fysik;

   Sammanfattning : This dissertation presents a serial study on optical properties of different semiconductor materials. Three main types of studies are addressed: The role of doping levels of N and Al atoms in the room-temperature photoluminescence (PL) of 4H-SiC films for optoelectronic applications; the use of a basic Monte Carlo method combined with probability calculations of the time-dependent Schroedinger equation to manifest multi-photon absorption and emission of II-VI compound quantum dots (QDs) for bioimaging; a theoretical quantum chemistry approach to study of structure and optical properties of InGaAsN and GaAs clusters for laser technology applications. LÄS MER

4. 3. Nanoelectronic Devices Based on Low-Dimensional Semiconductor Structures

   Författare :Daniel Wallin; Fasta tillståndets fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; InGaAs InP; GaAs AlGaAs; ballistic transport; quantum transport; low-dimensional structures; two-dimensional electron gas; quantum dot; three terminal ballistic junction; nanowire;

   Sammanfattning : The present thesis reports on results from the fabrication technology development and the corresponding electrical transport measurements of low-dimensional semiconductor structures. The focus of the work has been directed towards two parts: the ballistic transport in nanostructure devices at room temperature, and the development of a charge-sensing technique for quantum dots (QD) in nanowires. LÄS MER

5. 4. Magnetic frustration and low-dimensional magnetism : in transition metal fluorophosphates and square-lattice intermetallic compounds

   Författare :Stefanie Siebeneichler; Anja-Verena Mudring; Ulrich Häussermann; Sven Lidin; Kenneth R. Poeppelmeier; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; magnetic frustration; low-dimensional magnetism; ionothermal synthesis; powder neutron diffraction; fluorophosphates; intermetallics; Physical Chemistry; fysikalisk kemi;

   Sammanfattning : Solids can display a variety of vastly different magnetic properties. Besides the generally well known ferromagnets, antiferromagnets with their antiparallel arrangements of magnetic moments can exhibit a wide range of complex magnetic behavior such as magnetic frustration or low-dimensional antiferromagnetism. LÄS MER

7. 5. Quantum electronic transport in low-dimensional semiconductors

   Författare :Heiner Linke; Fasta tillståndets fysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; quantum transport; two-dimensional electron gas; contact-free characterisation; ballistic transport; mesoscopic; electron billiard; quantum dot; electron-electron interaction; non-linear; phase breaking; Halvledarfysik; Fysicumarkivet A:1997:Linke; non-symmetric conductio; Semiconductory physics; low-dimensional structures;

   Sammanfattning : Electronic transport is studied at low temperatures in two-dimensional electron gases (2DEGs) and in mesoscopic semiconductor microstructures. The method of microwave-detection of the Shubnikov-de Haas effect for the contact-free characterisation of transport properties of 2DEGs is explored using both magnetic-field modulation and light-induced carrier modulation. LÄS MER