Dresden 2006 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 23: Interfaces/surfaces
HL 23.4: Vortrag
Dienstag, 28. März 2006, 18:00–18:15, BEY 154
Quantitative characterization of a crystalline-amorphous interface by Q-HRTEM — •Karsten Thiel1, Nikolai Borgardt2, Boris Plikat3, Tore Niermann1, and Michael Seibt1 — 1IV. Physikalisches Institut der Universität Göttingen and SFB 602, Friedrich-Hund-Platz 1, 37077 Göttingen — 2permanent address: Moscow Institute of Electronic Technology, 103498 Moscow — 3now at: Infineon Technologies AG, 93049 Regensburg
The atomic structure of the transition region between c-Si(111) and a-Ge as well as a-Si has been studied by means of Q-HRTEM. Our approach involves averaging of the images along the interface, and simulating them within the "averaged-projected-potential" approximation by multi-slice simulation. This includes the use of a 2D-distribution function ρ(x,y) for the density of the atoms on the amorphous side and the well known atomic positions on the crystalline side.
ρ(x,y) reveals lateral ordering close to the crystalline substrate in addition to a pronounced layering. The width of both transition regions could be estimated to ≈1.4nm and the bond-angle distribution in the 1st layer is determined as 11.5∘ for a-Ge and ≈2.1∘ for a-Si.
For the a-Ge sample, we also investigated the lateral variations of ρ(x,y) and how far these changes are significant. It results, that there are no significant variations in the 1st atomic layer. This indicates homogenous properties for this layer on the scale of ≈23nm. In contrast, for the 2nd and 3rd layer we observe significant variations on a lateral scale of ≈10nm. We attribute these lateral variations to the response of the atomic network in the transition region on the volume misfit.