Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 65: 2D Materials 2: Growth, Structure and Substrate Interaction
O 65.7: Vortrag
Donnerstag, 8. September 2022, 12:00–12:15, S052
How the supple Pt(110) surface paves the way to single-domain h-BN growth. — •Marco Thaler1, Dominik Steiner1, Florian Mittendorfer2, and Erminald Bertel1 — 1Department of Physical Chemistry, University of Innsbruck, Austria — 2Institute of Applied Physics and Center for Computational Materials Science, Vienna University of Technology, Austria
Its structural flexibility renders Pt(110) an extraordinary substrate for hexagonal boron nitride (h-BN) growth. Borazine-exposure at high temperature yields either an extended film or empty terraces depending on dosage. Annealing preadsorbed Borazine, in contrast, yields nuclei with a structure differing from the extended film. DFT modelling of the latter was carried out by starting with a stretched film, which ruptured upon relaxation into smaller h-BN islands. The Pt surface layer below them is severely disordered. Only after high-T annealing the islands relaxe into the final h-BN/Pt(110)-(1xn) missing-row configuration. Thus, this non-classical, two-step nucleation proceeds via a metastable transition structure. Under the conditions of high-T exposure the metastable nuclei are continuously dissolved by desorption and H-induced etching. Stochastic formation of a critical island size with the more stable (1xn)m.r. structure requires a high supersaturation, but once formed, such an island grows explosively into an extended film. Hence, single-domain growth of h-BN on Pt(110) differs significantly from that on vicinal Cu(110), where (1-12) step edges act as nucleation sites giving rise to uniform nuclei capable of seamless coalescence.