Picosecond charge transport in rutile at high carrier densities studiedby transient terahertz spectroscopy

0464665 - FZÚ 2017 RIV US eng J - Journal Article
Zajac, Vít - Němec, Hynek - Kužel, Petr
Picosecond charge transport in rutile at high carrier densities studiedby transient terahertz spectroscopy.
Physical Review. B. Roč. 94, č. 11 (2016), 1-9, č. článku 115206. ISSN 1098-0121
R&D Projects: GA ČR GA13-12386S
Institutional support: RVO:68378271
Keywords : terahertz spectroscopy * charge transport * TiO₂ * rutile * ultrafast spectroscopy
Subject RIV: BM - Solid Matter Physics ; Magnetism
Impact factor: 3.736, year: 2014

We study terahertz photoconductivity of a rutile single crystal between 10 and 300 K under strong photoexcitation by femtosecond pulses at 266 nm. A marked dependence of the carrier mobility on the carrier density is observed leading to highly complex transport phenomena on a picosecond time scale. We develop a general model of carrier photoconductive response in the case of time dependent inhomogeneous distribution of carrier density and mobility. This allows us to assess an important role of both electrons and holes in the response of photoexcited rutile. At low temperatures, the carrier mobility is initially reduced due to the electron-hole scattering and increases by one order of magnitude upon ambipolar diffusion of the carriers into deeper regions of the sample. At room temperature, contributions of transient hot optical phonons and/or of midinfrared polaron excitations with charge-density-dependent dielectric strength emerge in the photoconductivity spectra.

Permanent Link: http://hdl.handle.net/11104/0263474