Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 6: Ge/Si I

HL 6.4: Talk

Monday, March 26, 2012, 10:15–10:30, EW 203

On the strain partitioning phenomenon in Ge clusters on free-standing Si(001) nanopillars — •Grzegorz Kozlowski¹, Peter Zaumseil¹, Andreas Schubert¹, Yuji Yamamoto¹, Joachim Bauer¹, Tobias Schulli², Bernd Tillack^1,3, and Thomas Schroeder^1,4 — ¹IHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany — ²European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex, France — ³Technische Universität Berlin, HFT4, Einsteinufer 25, Berlin 10587, Germany — ⁴Brandenburgische Technische Universität, Konrad-Wachsmann-Allee 1, 03046 Cottbus, Germany

Ge is attracting increasing interest to integrate photonic modules within Si chip baseline technology. The major stumble block is given by the 4.2% lattice mismatch. The theory of nanoheteroepitaxy (NHE) offers the vision to shift the critical thickness for defect nucleation in Ge to infinity by the so-called strain partitioning phenomenon. We report on the structural characterization of Ge clusters selectively grown by chemical vapor deposition on free-standing Si(001) nanopillars of 50 nm width. Synchrotron based x-ray diffraction studies and transmission electron microscopy were performed to experimentally verify NHE theory as a technique to grow high quality Ge on Si(001). Although the structure dimensions are comparable to the theoretical values required for the strain partitioning phenomenon, the compliant character of Si is not unambiguously proven. In consequence, the strain is relieved by nucleation of misfit dislocations at the Ge/Si interface. By gliding out of threading arms, high quality Ge nanostructures are achieved.