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HL: Halbleiterphysik
HL 23: Interfaces/surfaces
HL 23.1: Vortrag
Dienstag, 28. März 2006, 17:15–17:30, BEY 154
X-ray grazing incidence investigations of focused ion beam interactions with a Si and GaAs surfaces — •Jörg Grenzer1, Ullrich Pietsch2, Lothar Bischoff1, and Matthias Posselt1 — 1Forschungszentrum Rossendorf e.V., Institute of Ion Beam Physics and Materials Research, POB 51 01 19, D-01314 Dresden, Germany — 2FB7 - Physik , Universität Siegen, 57068 Siegen, Germany
We report on the study of a two-dimensional dot lattice structures which was produced on GaAs and Si (001) substrates using a Ga+ focused ion beam in normal incidence with a spot size of about 50 nm, an energy of 25 keV and a dose of 1014 cm−2. The fabricated 2D-lattice structures consist of dots of almost circular shape ( 2000 nm2) and a period of 250x250 nm2. We have investigated the interaction of the implanted ions with the host lattice as a function of the implantation conditions using grazing incidence diffraction at the ID10 and ID1 beam lines at the ESRF. The low-dose implantation creates interstitials and vacancies below the surface generating a weak displacement field resulting in a 2D periodical strain field in case of Si substrate. For the GaAs substrate we found a much more complex scattering pattern which depends on the in-plane orientation of the 2D dot lattice with respect to the substrate crystallographic orientation. A much stronger scattering contrast can be found if the 2D dot lattice misaligned by 14∘ degree. A simulation taking the interaction between the implanted ions and the host lattice into account shows an enhanced channelling of the ions into low-index crystallographic directions. Thus the dependence of the implantation damage profile on the crystalline structure influences the scattering patterns.