IRIDIUM SUBSTRATES FOR SPACE CONTAMINATION STUDIES: EROSION RATES UNDER ATOMIC OXYGEN EXPOSURE

摘要

Iridium metals films are currently being considered as substrates for the study of contamination layers deposited in the space environment. In situ spectroscopic ellipsometry has been applied to monitor the oxygen plasma etching of iridium/chromium/fused silica, using an electron cyclotron resonance plasma source to simulate the low earth orbital environment. The analyses of the spectroscopic Psi and Delta data at selected time slices suggest that the iridium film has been etched away gradually (～3.2 nm per year in LEO) upon plasma irradiation while showing no signs of oxidation or other chemical changes. Results indicate that, despite the thickness loss, iridium metals can indeed be used in space contamination studies.