Dresden 2003 – wissenschaftliches Programm
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O: Oberflächenphysik
O 29: Zeitaufgelöste Spektroskopie II
O 29.3: Vortrag
Donnerstag, 27. März 2003, 11:45–12:00, FOE/ORG
Surface Recombination Dynamics of SiO2/Si(100) - A Combined Laser and Synchrotron Radiation Study — •David Bröcker1, Tatjana Giessel1, Diana Pop1, Valentin Petrov1, Philipp Schmidt1, Bernd Winter1, and Wolf Widdra1,2 — 1Max-Born-Institut, Max-Born-Strasse 2a, 12489 Berlin — 2Institut für Atomare Physik und Fachdidaktik, TU Berlin
Localized states at the SiO2/Si interface are known to modify the valence and conduction bands which control many semiconductor phenomena and device properties. They also control the surface recombination of charge carriers after Laser excitation. This motivated a time-resolved study of band bending on this surface.
At the MBI-BESSY Beamline the recombination dynamics have been studied by pump probe electron spectroscopy. The second harmonic of a 1.25 MHz pulse picked Nd:YVO4 Laser system at 532 nm was synchronized to the synchrotron radiation pulses. The time window of 50 ps to 800 ns is limited by the pulse width and repetition rate of BESSY at single bunch.
After Laser excitation the surface photo voltage shows a non-exponential decay. With the recovery of band bending the charge carriers have to overcome a barrier for recombination, determined by the time dependent surface field. This leads to a self-decelerating decay process, which can be described and simulated by few well-understood parameters.