Berlin 2005 – scientific programme
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O: Oberflächenphysik
O 49: Epitaxie und Wachstum II
O 49.11: Talk
Tuesday, March 8, 2005, 18:15–18:30, TU EB407
Formation, propagation and stability of stacking fault defects in Iridium thin films — •Sebastian Bleikamp1, Celia Polop1, Arne Thoma1, Gerhard Pirug2, and Thomas Michely1 — 1I. Physikalisches Institut, RWTH Aachen, 52056 Aachen — 2Institut für Oberflächen und Grenzflächen, Forschungszentrum Jülich, 52425 Jülich
During homoepitaxial growth stacking fault islands are readily found on Ir(111). Upon coalescence defect structures are formed, which induce stacking fault propagation in subsequent layers.
To follow the fate of the twinned domains, a low energy electron diffraction (LEED) method is applied, which decomposes LEED I/V spectra into linear combinations of the non-equivalent first order diffraction peaks of the clean surface. The method was successfully calibrated versus STM measurements.
At 350K a film thickness of 50 monolayers is sufficient to create a nearly random mixture of twinned and untwinnned crystallites. Such films possess an impressive stability against thermal healing. Only at temperatures above 0.5 of the melting temperature, the fraction of twin crystallites gradually decreases. The stability of the faulted domains is discussed in relation to the structure of the twin boundaries formed.