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Abstract

In order to investigate the processes which determine preferential sputtering of compounds, changes of surface composition of Ta-2O-5 due to bombardment with 1.5 keV He**+ ions were studied as a function of the angle of incidence. Preferential sputtering was characterized by the equilibrium surface composition, measured by Auger electron spectroscopy, the characteristic fluence to reach equilibrium and the depth of the altered layer. For more grazing incidence of the ion beam a significant decrease of the preferential sputtering effect was observed. Changing the angle of incidence from 90 to 10 degrees relative to the surface changes the equilibrium Ta/O ratio by a factor of 3 and the characteristic fluence to reach equilibrium by a factor of 200. These results can be explained by the assumption that the sputtering is dominated by reflected particles, whose number and mean energy increase with decreasing angle of incidence. In the same angular range the depth of the altered layer decreases approximately by a factor of sin(PSI). Measurements of helium re-emission support the assumption that the depth of the altered layer corresponds to the damage profile of the bombarding ions. Dynamic changes of the surface composition can be explained by the superposition of the depletion curve and an equilibrium depth profile.

Additional information

Authors: BARETZKY B MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, GARCHING, MUENCHEN (GERMANY), MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, GARCHING, MUENCHEN (GERMANY)
Bibliographic Reference: WRITE TO MAX-PLANCK-INSTITUT FUER PLASMAPHYSIK, 8046 GARCHING BEI MUENCHEN (GERMANY), MENTIONING REPORT IPP 9/53, 1985
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