Direct observation of step-edge barrier effects and general aspects of growth processes: morphology and structure in diindenoperylene thin films deposited on Au(100) single crystals

Abstract

We investigate thin films of diindenoperylene deposited on Au(100) single crystals by using real time in situlow energy electron microscopy (LEEM) in synergy with X-ray photoelectron spectroscopy (XPS), and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. We find evidence for Stranski–Krastanov growth, with island nucleation prevalently at step bunches, and a lower probability of island nucleation at terraces. We also directly observe the effect of the Ehrlich–Schwoebel barrier at the substrate and in the film morphology, in particular inside the islands that show a non-homogeneous thickness due to a rough front growth, because of the additional energy required for the diffusing molecules to surmount a downward step.