Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 107: Semiconductor Surfaces (joint session O/HL)

O 107.2: Talk

Thursday, March 19, 2020, 15:15–15:30, REC C 213

Ion-Induced Surface Nanostructures of Germanium(001) — •Ricardo de Schultz, Denise Erb, and Stefan Facsko — Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden, Germany

Ion beam irradiation can lead to various self-organized surface nanopatterns depending on the irradiation conditions and the sample material. In this case, the surface patterns of Ge(001), which evolve during high-fluence 1 keV ion irradiation with Ar⁺ ions at elevated temperatures, have been studied. Whereas at room temperature the semiconductor surface would become amorphous during ion irradiation, high temperatures enhance the diffusion so that bulk vacancies and interstitials can recombine before the next ion hits the same surface region. Thus the surface stays crystalline. This results in a biased surface diffusion because of the Ehrlich-Schwoebel barrier at step edges and kinks.

The periodic surface patterns that emerge on Ge(001) reflect the four-fold symmetry of the crystalline surface. These patterns consist of a checkerboard of inward and outward oriented pyramids. For normal ion incidence their bases are square and oriented along the <100> crystal direction. For two different azimuthal ion incidence angles - along <110> and <100> - the emerging patterns have been examined for different polar incidence angles and compared to simulations. These indicate that the height gradient dependent sputter erosion plays an important role during pattern formation.