Application de techniques de diffusion elastique de particules alpha et d'ions lourds a l'analyse chimique des couches minces et des surfaces

Abstract : This work turns to account two aspects of the elastic scattering: Rutherford or non-Rutherford backscattering of alpha particles for the study of the stoechiometry of complex thin layers and production of recoil nuclei under energetic argon ion (16-20 MeV) bombardement for the surface analysis of light elements like oxyge nitrogen and carbon. The first section treats the analysis conditions of Ti$_(n-x)$Nb$_x$O$_2$ et Ti$_(l-x)$V$_x$O_$2$ layers whose composition depends on deposition parameters of the H.F. cathodic sputtering process of mixtures of oxide powders. In the firs place the analysis conditions of these layers were determined with the best possible accuracy: in the most favorable cases the concentration of oxygen and the the relative ratio of the metals sknown to better than 5%. As for the experimental results we show for the best deposition conditions (residual vacuum pre-sputtering) that the ratio O/(M+Ti) can be ajusted to 2$\pm$ 0.1 over all the target concentration ranges. The evolution of the radio Nb/(Nb+Ti) et V/(V+Ti) is not identical to that of targets with deviations whose significance we attempt to interprete. In the second section dealing with time of flight detection of recoil nuclei we justifiy our choice of experimental parameters by a detailed study of their influence on the analytical performances. In spite of serious limitations posed by angular dispersions the depth resolution typically varies from 2 to 5 nm for oxygen and carbon depending on wheter one deals with a matrix of medium Z(Si) or high Z(Ta). An energy discrimination serves at optimizing the analysable dephts and avoiding interferences (C,N and O analysable over 70 nm). This discrimination allows us to lower the detection limit (down to 10${13}$ at/cm$2$) by reduction of background noise. The current limitations and possible improvements are presented from surface analysis examples.
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Accelerator Physics. Université Claude Bernard - Lyon I, 1986. French


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Abderrahim Ziani. Application de techniques de diffusion elastique de particules alpha et d'ions lourds a l'analyse chimique des couches minces et des surfaces. Accelerator Physics. Université Claude Bernard - Lyon I, 1986. French. <tel-00744146>

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