IN-SITU X-RAY CHARACTERIZATION OF OLIGOPHENYLENE THIN-FILMS PREPARED BY ORGANIC MOLECULAR-BEAM DEPOSITION

In order to examine organic thin films during the deposition, we newly developed in situ observation system of an energy dispersive total re flection X-ray diffraction (TRXD) equipped with an organic molecular b eam deposition (OMBD). p-Sexiphenyl (6P), which is one of oligophenyle nes, is noted as a useful material with unique optical properties by c ontrolling the molecular orientation. To establish the method to contr ol the molecular orientation in 6P thin films prepared by OMBD, 6P thi n films on different substrates of silicon oxide (SiO2) and uniaxially oriented poly(p-phenylene) (PPP) were examined by using in situ TRXD. In the case of the 6P thin films prepared on SiO2, 6P molecules forme d with the normal orientation from the initial process of the depositi on. On the other hand, it was observed 6P molecules on the oriented PP P substrates formed with the parallel orientation along the PPP chains . By using out of plane measurements, it was revealed that the (20 (3) over bar) planes of 6P crystallites preferentially oriented parallel to the substrate surface. (C) 1998 Elsevier Science B.V. All rights re served.