Sökning: "impurities and defects"

Visar resultat 1 - 5 av 54 avhandlingar innehållade orden impurities and defects.

1. 1. Large and rare : An extreme values approach to estimating the distribution of large defects in high-performance steels

   Författare :Jens Ekengren; Jens Bergström; Christer Burman; Thomas Svensson; Karlstads universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Non-metallic inclusions; Tool steel; Extreme value statistics; Distribution of defects; Generalized extreme values; Materialteknik; Materials Engineering;

   Sammanfattning : The presence of different types of defects is an important reality for manufacturers and users of engineering materials. Generally, the defects are either considered to be the unwanted products of impurities in the raw materials or to have been introduced during the manufacturing process. LÄS MER

3. 2. Defects and Impurities in CdTe : An ab Initio Study

   Författare :Anna Lindström; Mattias Klintenerg; Susanne Mirbt; Biplab Sanyal; Peter Zahn; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Native defects; Compensation mechanisms; Semiconductor doping; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : In this thesis defects and impurities in CdTe have been studied with ab initio methods. CdTe is a II-VI semiconductor with many important applications such as γ- and X-ray detectors, solar cells and medical imaging. LÄS MER

4. 3. Growth and characterization of SiC and GaN

   Författare :Rafal Ciechonski; Erik Janzén; Sebastian Lourdudoss; Linköpings universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; SiC; GaN; Deep level transient spectroscopy; Minority Carrier Transient Spectroscopy; Hall effect; Cathodoluminescence; Scanning electron microscopy; Atomic Force microscopy; sublimation growth; MOCVD; heterostructures; High Electron Mobility transistor; point defects; Material physics with surface physics; Materialfysik med ytfysik;

   Sammanfattning : At present, focus of the SiC crystal growth development is on improving the crystalline quality without polytype inclusions, micropipes and the occurrence of extended defects. The purity of the grown material, as well as intentional doping must be well controlled and the processes understood. LÄS MER

5. 4. Influence of defects and impurities on the properties of 2D materials

   Författare :Soumyajyoti Haldar; Biplab Sanyal; Olle Eriksson; Torbjörn Björkman; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; 2D Materials; Defects on 2D materials; Impurities on 2D materials; Physics with spec. in Atomic; Molecular and Condensed Matter Physics; Fysik med inriktning mot atom- molekyl- och kondenserande materiens fysik;

   Sammanfattning : Graphene, the thinnest material with a stable 2D structure, is a potential alternative for silicon-based electronics. However, zero band gap of graphene causes a poor on-off ratio of current thus making it unsuitable for logic operations. This problem prompted scientists to find other suitable 2D materials. LÄS MER

7. 5. Graphene field-effect transistors and devices for advanced high-frequency applications

   Författare :Marlene Bonmann; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; traps; graphene; self-heating; field-effect transistors; remote phonons; carrier transport; saturation velocity; microwave devices; impurities and defects;

   Sammanfattning : New device technologies and materials are continuously investigated, in order to increase the bandwidth of high-speed electronics, thereby extending data rate and range of applications. The 2D-material graphene, with its intrinsically extremely high charge carrier velocity, is considered as a promising new channel material for advanced high frequency field-effect transistors. LÄS MER