Long‐Range Atomic Order on Double‐Stepped Al₂O₃(0001) Surfaces

Abstract

The deterministic preparation of highly ordered single‐crystalline surfaces is a key step for studying and utilizing the physical properties of various advanced materials. This paper presents the fast and straightforward preparation of vicinal Al2O3(0001) surfaces with micrometer‐scale atomic order. Crisp electron‐diffraction spots up to at least 20th order evidence atomic coherence on terraces with widths exceeding 1 µm. The unique combination of three properties of Al2O3(0001) underlie this remarkable coherence: its high‐temperature stability; the differences in the ionic bonding systems of the surface as compared to the bulk; and the fact that the terraces are non‐polar whereas the step edges have a polar character. The step edges are furthermore found to have alternating configurations, which drive a step‐doubling transition. On double‐stepped surfaces, the Al‐rich ° surface reconstruction attains a singular in‐plane orientation. These results set a benchmark for high‐quality surface preparation and thus expand the scope for both fundamental studies on and the technological utilization of exciting material systems.This article is protected by copyright. All rights reserved