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Thesis defense - Marjan Ilkov

Space-charge dynamics in microdiodes

  • 12.10.2015, 10:15 - 12:15

Marjan Ilkov will defend his doctoral thesis "Space-charge in microdiodes" Monday the 12th of October at 10:15 am in room M102.

Thesis committee:

Ágúst Valfells, Reykjavík University
Andrei Maolescu, Reykjavík University
Viðar Guðmundsson, University of Iceland

Examiner:

Allen L. Garner, Purdue University.

Abstract:

Space-charge limited emission in vacuum microdiodes can go through longitudinal modulation under certain conditions. The frequency of this modulated current is in the terahertz band and it can be tuned by changing either the the gap spacing or the gap voltage of the diode. Doing the latter is the preferred mode of operation during the simulations which we did. As the power of such diode radiators would be very small, we coupled arrays of such diodes and showed that such an array, which synchronizes itself, can give powerful enough radiation for practical usage. 

For the emission process, it was first assumed that electrons would be emitted with zero initial velocity, as such an assumption is readily used in most emission calculations in the room temperature range. To further the research, we assumed non-zero initial velocities for the photoemitted electrons and found that, although, not without effect, the non-zero initial velocity does not significantly reduce the power of the radiator. The spatial structure of the beams was examined as well. Finally, a code for simulation of the space-charge effects in solar cells was tested, and although at present no claims can be made about these effects, the code proved to be a very good tool which replicated results from experiments and theory alike. 








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