Regensburg 2010 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 2: SC: Applications and Measuring Devices
TT 2.5: Vortrag
Montag, 22. März 2010, 11:15–11:30, H19
Energy relaxation processes in YBCO thin films studied by frequency and time-domain techniques — •Petra Probst1, Dagmar Rall1,2, Matthias Hofherr1, Stefan Wünsch1, Konstantin Ilin1, and Michael Siegel1 — 1Institut für Mikro- and Nanoelektronische Systeme, Karlsruher Institute of Technology, Hertzstrasse 16, 76187 Karlsruhe, Germany — 2Lichttechnisches Institut, Karlsruher Institute of Technology, Engesserstrasse 13, 76131 Karlsruhe, Germany
The development of ultra-fast detectors with time resolutions in the picosecond range requires the analysis and understanding of the dynamics in the energy relaxation processes in thin films. A systematic study of the energy relaxation processes in YBCO thin films on sapphire substrate has been performed. Pulsed-laser deposited YBCO samples between 20 and 60 nm film thickness were fabricated and characterized by means of frequency and time domain techniques by excitation of the samples with optical radiation. The characteristic energy relaxation time was extracted from the thin film sample response according to the two-temperature model. The extracted time constants of the two techniques showed good agreement. We have observed an increase of the energy relaxation time from 500 ps to 4 ns with increase of the film thickness from 20 to 60 nm, respectively. The obtained dependence of the characteristic time on film thickness we attribute to the escape of non-equilibrium phonons from the YBCO films into substrate. Details of the experimental methods and results on the energy relaxation in thin YBCO films and the applied theoretical model will be discussed.