Dresden 2003 – wissenschaftliches Programm
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DS: Dünne Schichten
DS 10: Laserverfahren zur Schichtherstellung und Oberfl
ächenmodifizierung II
DS 10.5: Vortrag
Dienstag, 25. März 2003, 11:15–11:30, GER/37
Laser nitriding and laser carburization of Silicon — •Ettore Carpene and Peter Schaaf — II. Physikalisches Institut, Universität Göttingen, Bunsenstrasse 7/9, 37073, Göttingen, Germany
The technological importance of silicon carbide (SiC) and silicon nitride (Si3N4) has stimulated the scientific attention on the synthesis of these materials. The excellent thermal stability, the good chemical resistance at high temperatures and the large band gap of SiC make it extremely attractive for high power applications. On the other hand, the superior corrosion resistance, the thermal and the mechanical properties of all polymorphs of Si3N4 enhanced the use of this ceramic in many different fields such as automobile engineering, cutting tools and nuclear reactors. It will be presented how laser irradiation of single-crystalline silicon substrates in controlled nitrogen and methane atmospheres leads to the formation of such carbide and nitride phases. The analyses have been performed mainly by Extended X-ray Absorption Fine Structure (EXAFS) due to the high sensitivity of this technique to the local atomic environment. The incorporation of carbon in the silicon matrix leads to the formation of polycrystalline cubic SiC (β-SiC) with a good degree of crystallinity. The carbide phase is mixed with non-reacted silicon and its relative fraction is estimated as a function of the number of laser shots and the methane pressure. The irradiation in nitrogen atmosphere produces highly disordered or amorphous silicon nitride layers with thicknesses of the order of a few tens of nanometers. The morphology of these samples is strongly correlated to the nitrogen mass transport mechanisms.