Ultrafast terahertz photoconductivity in nanocrystalline mesoporous TiO.sub.2./sub. films

0342062 - FZÚ 2011 RIV US eng J - Journal Article
Němec, Hynek - Kužel, Petr - Kadlec, Filip - Fattakhova-Rohlfing, D. - Szeifert, J. - Bein, T. - Kalousek, Vít - Rathouský, Jiří
Ultrafast terahertz photoconductivity in nanocrystalline mesoporous TiO₂ films.
Applied Physics Letters. Roč. 96, č. 6 (2010), 062103/1-062103/3. ISSN 0003-6951. E-ISSN 1077-3118
R&D Projects: GA ČR(CZ) GP202/09/P099; GA AV ČR(CZ) IAA100100902; GA ČR GA104/08/0435; GA ČR GD203/08/H032
Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z40400503
Keywords : time-resolved terahertz spectroscopy * ultrafast photoconductivity * TiO₂ nanoparticles * brick and mortar technology
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.820, year: 2010

Terahertz time-resolved spectroscopy is used to investigate the transport of photoexcited electrons in nanocrystalline mesoporous TiO2 films prepared by the recently proposed "brick and mortar" technology [Szeifert et al. Chem. Mater. 21, 1260 (2009)] with a variable fraction of nanocrystalline titania "bricks" and amorphous titania "mortar". Both long- and short-range conductivity is significantly enhanced upon calcination. After an ultrafast (subpicosecond) regime where the intrananograin conductivity dominates, the electron conductivity becomes limited by the interaction of electrons with the amorphous mortar. Comparison of the experimental results with Monte Carlo simulations of the electron motion allows us to determine the crystalline grain size after calcination and the yield of mobile photocarriers.
Permanent Link: http://hdl.handle.net/11104/0184890