Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 50: Ultra fast phenomena
HL 50.1: Vortrag
Freitag, 27. März 2009, 10:15–10:30, BEY 118
Femtosecond Pump-Probe Spectroscopy of ZnO Thin Films — •Sumedha Chouthe1, Chris Sturm2, Gerhard Seifert1, Rüdiger Schmidt-Grund2, Marius Grundmann2, and Heinrich Graener1 — 1Optics Group, Institute for Physics, Martin-Luther-University Halle-Wittenberg, Hoher Weg 8, D-06129 Halle, Germany — 2Institute for Experimental Physics-II, University of Leipzig, Linnestraße 5, D-04103 Leipzig, Germany
ZnO being a direct n-type semiconductor with a large energy gap of ~3.4eV has several applications such as in short wavelength light emitting devices. In this work, the ultrafast carrier dynamics in ZnO film are investigated using femtosecond time resolved transmission pump probe spectroscopy. The ZnO thin film with thickness of 500nm was grown on sapphire substrate by means of pulsed laser deposition. Complete dielectric function of the sample was determined from detailed analysis of ellipsometric and transmission measurements. In the pump-probe set up, frequency doubled Ti:Sa laser pulses at λ=400nm were used as pump (Epump=46μJ, pulse width=150fs) to excite the sample, and femtosecond supercontinuum light (320-560nm) probed the transmission changes in the sample. A complicated time evolution of the spectral changes is observed. Four contributions are needed to understand the time resolved results. Analysis of temporal evolution of different processes allows detailed insight into the electron dynamics in ZnO film initiated by the λ=400nm femtosecond laser pulse.