Stuttgart 2012 – scientific programme
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K: Fachverband Kurzzeitphysik
K 8: Poster II
K 8.5: Poster
Thursday, March 15, 2012, 16:30–18:30, Poster.V
Femtosecond laser pulse interaction with hydrogenated amorphous silicon (a-Si:H) thin films — •Babak Soleymanzadeh1, Christof Neumann1, Christian Strüber1, Matthias Hensen1, Pavel Prunici2, Andreas Gondorf2, Helmut Stiebig1,2, and Walter Pfeiffer1 — 1Physik Fakultät, Universität Bielefeld, Universitätsstraße 25, 33615 Bielefeld — 2Malibu GmbH & Co. KG, Böttcherstraße 7, 33609 Bielefeld
Femtosecond laser pulse interaction with thin films of hydrogenated amorphous silicon (300nm thickness) is investigated. Amplified ultrashort laser pulses (from 0.04mJ to 0.13mJ pulse energy, 800nm centre wavelength, 40fs pulse duration) are focussed onto the surface either using a parabolic mirror or a lens leading to focus diameters of 15µm and 105µm, respectively. The laser treated spots are analyzed by optical microscopy (OM), scanning electron microscopy (SEM), Raman spectroscopy, and height profilometry. The ablation threshold increases significantly with focus diameter from < 300mJcm−2 for the small focus diameter to >400mJcm−2 for the large one. Well below the ablation threshold the recrystallization of the amorphous layer and a significant surface swelling is observed. Applying the same total fluence distributed on two consecutive pulses (1ms separation) also changes the ablation behavior. The laser induced surface swelling and the topography of the ablation spots indicate that the laser induced release of hydrogen strongly influences the ablation dynamics.