MORPHOLOGY OF P-HEXAPHENYL THIN-FILMS

The poly(p-phenylene) oligomer p-hexaphenyl is used in electroluminesc ent devices emitting intense blue light. The defined thin film crystal growth of hexaphenyl is studied under certain conditions. Thin films are grown by physical vapor deposition on various substrates (GaAs, IT O). The influence of the substrate temperature (room temperature to 17 0 degrees C) and film thickness (up to 6000 Angstrom) on the nature of the crystal growth is studied. The film properties, like nucleation, coverage, crystal dimensions, shape and appearance, are characterized by scanning electron microscopy (SEM). We discuss the influence of the type of substrate and its surface on the film growth and morphology. The crystal structure of these films was determined by X-ray diffracti on. The crystallites' dimensions and surfaces are studied with atomic force microscopy (AFM).