Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 32: Epitaxie und Wachstum II

O 32.1: Vortrag

Donnerstag, 27. März 2003, 15:00–15:15, FOE/ANOR

Interplay of surface morphology and strain relief during epitaxial growth of Ge on Si(001) — •M. Horn-von Hoegen, T. Grabosch, P. Kury, M. Horn-von Hoegen, T. Grabosch, and P. Kury — Inst. f. Laser- u. Plasmaphysik, Uni Essen

The lattice mismatch of 4.2% between Si and Ge plays a crucial role during any kind of hetero-epitaxial growth in this system. Ge starts to grow as a pseudomorphic film in a layer-by-layer fashion followed by the formation of coherent islands, however, at some critical coverage plastic relaxation occurs via the generation of misfit dislocations and the islands start to coalesce. These different stages of strain relief mechanism have been studied in-situ during growth of Ge films at 500^∘C on thin Si(001) substrates using a Laser deflection technique SSIOD and SPA-LEED. The wetting layer shows a film stress of 1 NmML_Ge⁻¹ which agrees well with the value expected from bulk Ge. The formation of Hut clusters sets in at 4 ML_Ge. No additional film stress is built up during this stage. At 8 ML_Ge the entire surface is covered with hut clusters. Then the formation of dome clusters allows an additional strain relieve of 85%. With Sb or As as a surfactant thicker coherent and smooth Ge films can be grown without islanding or defect generation. This change of growth mode is also apparent in the evolution of the stress signal.