Influence of surface morphology on angular photo-electron spectroscopy measurements of nanometer thin overlayers

In order to investigate the boundaries of our angle-resolved analyzer, we have prepared a variety of surface morphologies that are relevant for a wide class of surfaces in many research areas. These specimens are used as a template to be covered with a bi-layer that is exhibiting perfect overlayer behavior when coated on a smooth template and with an overlayer that is expected to react with the template material. These sets are in-vacuum characterized with angle-resolved photo-electron spectroscopy. Furthermore, the morphologies of both sets are characterized by atomic force microscopy. All experimental data as well as a model including a gradient interface between overlayer and substrate layer are used to discuss the limits of interpreting our angle-resolved data with non-smooth surfaces. It will be argued that this apparently wrong model for surface roughness can still be used to estimate the surface morphology when additional information is available either by prior knowledge of the growth behavior or by chemical information within the photo-electron measurements. Copyright © 2014 John Wiley & Sons, Ltd.