Picosecond Processes of Laser‐Excited Carriers in Silicon on Sapphire

The relaxation processes on a ps-time scale in silicon on sapphire, ion-beam damaged SOS and hydrogenated ion-beam damaged SOS are studied by means of time-resolved reflectivity and photoconductivity measurements. The excitation wavelength is changed to excite the carriers either near to the band edge or into the conduction band. Therefore, it is able to distinguish between different relaxation processes. The results can be explained using a 4-level model. The influence of the amorphization of samples on the relaxation time is discussed. Es werden Relaxationsprozesse in Silizium auf Saphire (SOS), ionenstrahlzerstortem SOS und hydrogenisiertem ionenstrahlzerstortem SOS im Pikosekundenbereich mit Hilfe von zeitaufgelosten Reflexions- und Photoleitfahigkeitsmessungen untersucht. Unter Verwendung der frequenzverdoppelten Strahlung eines optisch parametrischen Verstarkers, der von der zweiten Harmonischen eines Nd:YAG-Lasers gepumpt wird, werden die Ladungstrager entweder zur Leitungsbandkante oder ins Leitungsband hinein angeregt. Dadurch konnen unterschiedliche Relaxationsprozesse untersucht werden. Der Einflus des Amorphisierungsgrades auf die Relaxationszeit wird diskutiert.

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