Structure of the Buried Metal-Molecule Interface in Organic Thin Film Devices

By use of specular X-ray reflectivity (XR) the structure of a metal-covered organic thin film device is measured with angstrom resolution. The model system is a Langmuir−Blodgett (LB) film, sandwiched between a silicon substrate and a top electrode consisting of 25 A titanium and 100 A aluminum. By comparison of XR data for the five-layer Pb2+ arachidate LB film before and after vapor deposition of the Ti/Al top electrode, a detailed account of the structural damage to the organic film at the buried metal−molecule interface is obtained. We find that the organized structure of the two topmost LB layers (∼5 nm) is completely destroyed due to the metal deposition.