Etude par microanalyse ionique de films de poly(paraphénylène) et des phénomènes induits par implantation ionique

Ion implantation in conjugated polymers: Mechanisms for generation of charge carriers

“…There is some variation in the results for the larger ions (xenon) where a slight increase near low energy (50 keV) is apparent; as previously mentioned, this small effect can be related to the approximate assessment of R , and ARp; near the surface the porous nature of material gives a lower density than the bulk value used for calculations whose results ( R , and AR,) are therefore underestimated. With a larger value of AR, (in agreement with that experimentally obtained by SIMS (Ratier et al 1992a) at a low implantation energy) we find again the same behaviour as for light ions implanted more deeply and where the porous nature of the surface does not play a major role any more.…”

“…This is well recognized in the study of the structure and electronic structure of amorphous carbon (Robertson 1986). In the context of structural changes produced by ion implantation in PPP, we note that there is evidence for hydrogen loss (Ratier et al 1992a), and we consider that the majority of the bond scission will indeed leave the aromatic rings intact. This is expected when the energy-loss mechanism is through electronic excitations, since the Auger excitation from the carbon K shell is not expected to disrupt the aromatic ring (Mohd Muhid et al 1988).…”

“…It has not, however, proved to be an easy material to process since it cannot be solution processed directly. Pressed pellets PPP synthesized by the method of Kovacic and Kyriakis (1963) and Kovacic and Jones (1987) have been extensively used (Froyer et al 1987, Duroux et al 1988a, Duroux, Moliton and Froyer 1988b, Moliton, Ratier, Guille and Froyer 1990b, Moliton, Ratier, Moreau and Froyer 1991, Le Hue et al 1992, Ratier et al 1992a, b, Ratier, Moliton, Guille and Froyer 1992c. Electrochemical polymerization of para-dibromobiphenyl onto conducting substrates has been used to prepare thin films (Ratier, Pelous, Froyer and Moliton 1991).…”

“…Information about the microscope nature of the structural changes in PPP is limited at present. Secondary-ion mass spectrometry (SIMS) does, however, show that there is significant loss of hydrogen in relation to the carbon present under all the conditions ofimplantation (Ratier et al 1992a); this indicates that the C-H bonds are relatively easily broken. We note that loss of hydrogen is seen in many other polymers (Davenas and Thevenard 1993) and is also seen in electron beam damage studies on conjugated molecules such as terphenyl and coronene, for which the damage cross-section follows the carbon K-shell ionization cross-section (Mohd Muhid, Howie, Rocca and Valdre 1988).…”