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MM: Fachverband Metall- und Materialphysik
MM 60: Topical Session: In Situ and Multimodal Microscopy in Materials Physics III
MM 60.4: Talk
Thursday, March 21, 2024, 16:30–16:45, C 130
Field ion microscopy contrast for Boron in Silicon — •Christoph Freysoldt1, Shalini Bhatt1, Jonathan Op de Beeck2, Claudia Fleischmann2, and Jörg Neugebauer1 — 1Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40273 Düsseldorf — 2Imec, Kapeldreef 75, and KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
Field ion microscopy (FIM) has been recently shown to improve atom probe tomography (APT), by imaging surface atoms prior to evaporation. This helps to elucidate dynamical surface evolution in APT, and the reconstruction artifacts that may result. In FIM, an imaging gas above the surface is ionized via electron tunneling into empty surface states. The ion flux images individual surface atoms as bright spots. The challenge in FIM is to relate contrast in gas ionization to the relevant atomic surface configurations. We study this here for the case of Boron-doped Silicon, where APT suggests an unintended clustering of the dopants. In FIM experiments with H2 as imaging gas, a variety of bright features appears upon doping, but the nature of the surface configuration and the source of the contrast is not known. We investigate possible different surface configurations of Boron with density functional theory, as well as their appearance in FIM based on our recent EXTRA-FIM package[1]. We show that electronic structure effects cannot explain the observed bright imaging, and suggest that Boron produces exposed surface clusters during evaporation due to the high strength of Si-B bonds, that hinder homogeneous evaporation.
[1] S. Bhatt et al., Phys. Rev. B 107, 235413 (2023).
Keywords: field ion microscopy