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DS: Fachverband Dünne Schichten

DS 8: Thin Film Characterisation: Structure Analysis and Composition (XRD, TEM, XPS, SIMS, RBS, ...) I

DS 8.5: Vortrag

Montag, 14. März 2011, 11:15–11:30, GER 38

Nucleation Mechanisms In High Energy Ion Beam Induced Dewetting — •Michael Haag, Daniel Garmatter, Redi Ferhati, Sankarakumar Amirthapandian, and Wolfgang Bolse — Institut für Halbleiteroptik und Funktionelle Grenzflächen, Universität Stuttgart

Solid coatings, when heated above their melting points, often break up by forming small round holes, which then grow, coalesce and finally turn the initially contiguous film into a pattern of isolated droplets. Such dewetting has been intensively studied using thin polymer films on Si [1]. Three different hole nucleation mechanisms were discovered: homogeneous (spontaneous) nucleation, heterogeneous nucleation at defects, and spinodal dewetting by self-amplifying capillary waves. We have recently found that swift heavy ion (SHI) irradiation of thin oxide films on Si results in similar dewetting patterns, even though the films were kept far below their melting points [2]. Using our new in-situ SEM at the UNILAC accelerator of GSI [3], we were now able to identify the mechanisms behind this SHI induced dewetting phenomenon. By varying the film thickness and introducing defects at the interface, we can directly address the hole nucleation processes. Besides homogeneous and heterogeneous nucleation, we also found a process, which very much resembles the spinodal mechanism found for liquid polymers, although in the present case the instable wavy surface is not generated by capillary waves, but by ion beam induced stresses. [1] S. Herminghaus, et al., Science 282 (1998), [2] T. Bolse, et al., Nucl.Instr.Meth. 245 (2006), [3] S. Amirthapandian, et al., Rev.Sci.Instr. 81, (2010)