Temperature-Induced Structural Transitions on Hybrid Nanothick Metal/Polymer Assemblies

Performance of nanothick metal/polymer assemblies crucially depends on the internal structure of the metal polymer assemblies. As only a combination of high sensitive techniques is able to access the fine structure changes, combined X-ray reflectivity (XRR) and electrical AFM analysis are proposed. This combination of techniques is used to follow the fine evolution of the nanostructure of an ultrathin gold layer (10 nm) deposited on a polystyrene thin film (30 nm) as a function of the metal deposition temperature (from T-d = -40 to 220 degrees C). Nanothick metal/polymer assemblies are prepared by evaporating ultrathin gold layer (<10 nm) onto spin-coated polystyrene thin film (h < 40 nm). Surface roughness evolution with increasing deposition temperature studied by atomic force microscopy (AFM) clearly shows a maximum corresponding to the expected glass transition temperature of the polystyrene film. X-ray reflectivity (XRR) measurements are used to follow the progressive embedment of the gold particles into the polymer film when the deposition temperature increases above the T-g of the polymer film. Consequences of the structural evolution of the assembly are then emphasized by measuring with an AFM the increase of surface electrical resistivity of the assembly when the gold embedment is progressing.