Sökning: "hot electrons"

Visar resultat 1 - 5 av 33 avhandlingar innehållade orden hot electrons.

  1. 1. Time-Resolved Photoemission Electron Microscopy: Development and Applications

    Författare :Lukas Wittenbecher; NanoLund; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; PEEM; time-resolved PEEM; ultrafast optics; pulse shaping; plasmonics; semiconductor nanowires; hot electrons; ultrafast microscopy; charge carrier relaxation;

    Sammanfattning : Time-resolved photoemission electron microscopy (TR-PEEM) belongs to a class of experimental techniquescombining the spatial resolution of electron-based microscopy with the time resolution of ultrafast opticalspectroscopy. This combination provides insight into fundamental processes on the nanometer spatial andfemto/picosecond time scale, such as charge carrier transport in semiconductors or collective excitations ofconduction band electrons at metal surfaces. LÄS MER

  2. 2. NbN and NbTiN Hot Electron Bolometer THz Mixers

    Författare :Pourya Khosropanah; Chalmers University of Technology; []
    Nyckelord :receiver noise; hot electron bolometer; superconducting detector; spiral antenna; NbTiN; submillimeter mixer; THz mixer; HEB; FTS; NbN; quasioptical receiver; heterodyne receiver; double slot antenna; twin slot antenna; Fourier Transform Spectrometer;

    Sammanfattning : The thesis reports the development of Hot Electron Bolometer (HEB) mixers for radio astronomy heterodyne receivers in THz frequency range. Part of this work is the fabrication of HEB devices, which are based on NbN or NbTiN superconducting thin films (≤5 nm). They are integrated with wideband spiral or double-slot planar antennas. LÄS MER

  3. 3. Charge Separation on Localized Surface Plasmon and Hot Carrier Transfer to Semiconductors

    Författare :Yocefu Hattori; Jacinto Sá; Stephan Link; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Plasmonics; hot carrier; metal nanoparticles; semiconductors; ultrafast transient absorption spectroscopy; Chemistry with specialization in Physical Chemistry; Kemi med inriktning mot fysikalisk kemi;

    Sammanfattning : The relatively recent discovery that plasmonic nanoparticles generate energetic electron-hole pairs known as hot carriers has been the source of interest from many scientific groups. The capability to extract these short-lived hot carriers from metal nanoparticles (NPs) might potentially lead to applications in solar cells, photodetection, and photocatalysis. LÄS MER

  4. 4. Thermoelectric- and hot-electron effects in graphene devices

    Författare :Grigory Skoblin; Chalmers University of Technology; []
    Nyckelord :NATURVETENSKAP; TEKNIK OCH TEKNOLOGIER; NATURAL SCIENCES; ENGINEERING AND TECHNOLOGY; Parylene; bolometer; CVD; encapsulation; graphene; thermoelectric effects;

    Sammanfattning : A technology of encapsulation of graphene in Parylene was introducedas an alternative to encapsulating graphene in hBN. Edge contacts to theencapsulated graphene in this case showed resistivity down to 14 Ohm um,which is the lowest reported value so far. LÄS MER

  5. 5. Suprathermal Electrons and Alfvén Eigenmodes in Sawtoothing Tokamak Plasmas

    Författare :Patrik Sandquist; Chalmers University of Technology; []
    Nyckelord :magnetohydrodynamic spectroscopy; Alfvén cascade; suprathermal electron; thermonuclear instability; Fusion plasma physics; fast electron bremsstrahlung; toroidal Alfvén eigenmode;

    Sammanfattning : In the Joint European Torus (JET) tokamak, monster sawtooth stabilisation by ICRH-accelerated hot ions is lost if plasma density falls below a certain density threshold, or if energetic-ion driven Alfvén eigenmodes inside q = 1 occur. In the first case, a transition away from long periodmonster sawteeth to a regime with shorter period, chaotic sawteeth (grassy sawteeth) takes place, while in the second case the monster sawtooth crash happens, degrading plasma confinement. LÄS MER