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Thin oxide layers were produced by exposures of polished and sputter-cleaned stainless steel sample to approximately 10-5 mb oxygen administered into the fast entry chamber previously pumped down to 10-8 mb. XPS depth profiling determined principal constituents of the oxide layer as chromium and iron oxides and estimated layers to be very thin (of the order of 1 - 2 nm). This was corroborated by AES depth profiling. Since thickness estimations in depth profiling depend on sample’s stoichiometry which, in turn, may be changed by process of profiling measurement itself, two non destructive techniques were used as an independent non-destructive verification of at least oxide layers' thicknesses. First, simple graphical Thickogram method was employed to derive oxide layer thickness from given emission angle. Then, full ARXPS was attempted. For instrument that was used, a special tilted sample holder had to be manufactured to translate instrument's available sample tilt into emission angle range 0 - 75o. Thus, sets of metallic/oxide peaks from Fe 2p3/2 and Cr 2p3/2 were measured for different angles. From these measurements, thickness estimations were derived that roughly agree with depth profiling data and thickness estimations obtained by Thickogram method. There are, however, some deviations from linearity, which may point to problems with smoothing and/or cleaning procedures. |