Preparation of smooth Fe (001) on MgO (001)

Abstract.

The high mobility of metal adsorbates on perfect oxide surfaces favours an island-growth mode, which results in a granular morphology for metallic thin films. At low temperature, a fast substrate coverage is achieved due to the reduced mobility which, on the other hand, inhibits the development of an atomically smooth surface. In this study we used a controlled procedure to grow smooth epitaxial films of a few nanometres of Fe on MgO (001). The development of the dynamic conductivity as a measure of morphological roughness was observed during metal deposition by means of in-situ infrared spectroscopy. At various steps of thin-film preparation we used low-energy electron diffraction (LEED) for a characterisation of the crystalline surface quality. With ex situ atomic force microscopy (AFM) we investigated the surface topology of the prepared films with respect to smoothness. For example, for a controlled-growth 2-nm film, we observed a sharp LEED pattern and a metallic dynamic conductivity, and we did not find the distinct grooves which are characteristic of a granular structure.