THz photoconductivity in light-emitting surface-oxidized Si nanocrystals: the role of large particles

0439724 - FZÚ 2015 RIV DE eng J - Článek v odborném periodiku
Zajac, Vít - Němec, Hynek - Kadlec, Christelle - Kůsová, Kateřina - Pelant, Ivan - Kužel, Petr
THz photoconductivity in light-emitting surface-oxidized Si nanocrystals: the role of large particles.
New Journal of Physics. Roč. 16, Sep (2014), "093013-1"-"093013-25". ISSN 1367-2630. E-ISSN 1367-2630
Grant CEP: GA ČR GPP204/12/P235; GA ČR GA13-12386S
Institucionální podpora: RVO:68378271
Klíčová slova: ultrafast photoconductivity * Si nanocrystals * charge carrier transport * terahertz spectroscopy
Kód oboru RIV: BM - Fyzika pevných látek a magnetismus
Impakt faktor: 3.558, rok: 2014

We propose an analytical description of the role of local depolarization fields in the terahertz conductivity of nanostructured samples and demonstrate this approach in a sample composed of silicon nanocrystals fabricated by electrochemical etching of silicon wafer followed by an oxidizing treatment. The post-etching treatment leads to a decrease in the average nanocrystalline Si core size which enhances luminescence in the visible range. We show that the dominating microscopic photoconductive response of photocarriers is essentially Drude-like owing to the presence of a very small amount of large nanocrystals; the macroscopic character of the response is, however, deeply modified by the depolarization fields. Smaller nanocrystals appreciably con- tribute to the terahertz conductivity only at high photoexcitation densities where the screening due to depolarization fields suppresses the response of the large particles.
Trvalý link: http://hdl.handle.net/11104/0242943