Relativistic Doppler reflection as a probe for the initialrelaxation of a non-equilibrium electron-hole plasma in silicon
2015 (English)In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 647, 012016-012019 p.Article in journal (Refereed) Published
This paper reviews the status of investigations of the relativistic Doppler reflectionof a broadband terahertz pulse at a counter-propagating plasma front of photo-excited chargecarriers in undoped silicon. When a THz pulse with 20-THz bandwidth impinges onto amoving plasma front with a carrier density in the range of 1019 per cm3, one observes a spectralup-shift, which is, however, much less pronounced than expected from simulations assuming a Drude plasma characterized by a single carrier relaxation time τ of the order of 15-100 fs.Qualitative agreement between simulations and experiments can be achieved if τ is chosen tobe less than 5 fs. In order to explore carrier relaxation in more detail, optical-pump/THz-probeexperiments in the conventional co-propagation geometry were performed. If the pump-probedelay is long enough for monitoring of the equilibrium value of the scattering time, τ rangesfrom 200 fs at low carrier density to 20 fs in the 1019-cm-3 density range. For small (subpicosecond)pump-probe delay, the data reveal a significantly faster scattering, which slowsdown during energy relaxation of the charge carriers.
Place, publisher, year, edition, pages
Institute of Physics (IOP), 2015. Vol. 647, 012016-012019 p.
Relativistic Doppler reflection, non-equilibrium electron-hole plasma, relaxation, silicon.
Condensed Matter Physics
IdentifiersURN: urn:nbn:se:liu:diva-123876DOI: 10.1088/1742-6596/647/1/012016ISI: 000366236800016OAI: oai:DiVA.org:liu-123876DiVA: diva2:893554
19th International Conference on Electron Dynamics in Semiconductors, Optoelectronics and Nanostructures (EDISON'19), Salamanca, Spain, 29 June to 2 July 2015
FunderGerman Research Foundation (DFG)