The surface structure of alpha-Al2O3 determined by low-energy electron diffraction: aluminum termination and evidence for anomolously large thermal vibrations

摘要

We have determined the surface structure of alpha -Al2O3(0001) using dynamical low-energy electron diffraction (LEED). Sapphire surfaces were prepared in three different ways, and the diffraction results were analyzed using an exhaustive search of possible models. For all sample processing conditions, the clearly favored structure has a single aluminum layer termination and a large first interlayer contraction. In addition, we find that the surface atoms have unusually large vibrational amplitudes at room temperature, suggestive of an anharmonic vibrational mode. (C) 2000 Elsevier Science B.V. All rights reserved. References: 28