Morphology and interdiffusion behavior of evaporated metal films on crystalline diindenoperylene thin films

Abstract

We present a transmission electron microscopy (TEM)/Rutherford backscattering spectrometry (RBS)/x-ray-diffraction (XRD) study of Au evaporated on crystalline organic thin films of diindenoperylene (DIP). Cross-sectional TEM shows that the preparation conditions of the Au film (evaporation rate and substrate temperature) strongly determine the interfacial morphology. In situ XRD during annealing reveals that the organic layer is thermally stable up to about 150 °C, a temperature sufficient for most electronic applications. The x-ray measurements show that the “as-grown” Au layer exhibits a large mosaicity of around 10°. Upon annealing above ≈120 °C the Au film starts to reorder and shows sharp (111)-diffraction features. In addition, temperature dependent RBS measurements indicate that the Au/DIP interface is thermally essentially stable against diffusion of Au in the DIP layer up to ≈100 °C on the time scale of hours, dependent on the Au thickness.