Properties of oxide thin films and their adsorption behavior studied by scanning tunneling microscopy and conductance spectroscopy

This article surveys state-of-the-art STM experiments aiming for an investigation of surface properties of oxide materials as well as their interaction with individual adatoms, molecules and metal particles. It provides an introduction into the nucleation and growth of oxide layers on single-crystalline metal substrates, putting special emphasis on the various relaxation mechanisms of the oxide lattice to release the misfit strain with the support. Additionally, the peculiarities of polar oxide films are discussed. In the second part, the different interaction schemes between oxide surfaces and adsorbates are presented from the theoretical point of view as well as on the basis of the key experiment performed with the STM. The focus lies hereby on charge-mediated binding schemes, leading to the formation of cationic or anionic species on the oxide surface. Furthermore, the role of point and line defects in the oxide adsorption behavior is inferred. The potential of thin oxide films as systems with tunable physical and chemical properties is highlighted at the end of this review.