Depth Composition

This has been used, for instance, to follow the formation of palladium silicide in a silicon wafer for thicknesses up to 6nm [Vanleerdam et al., 1990]. More recently, investigation of the tails in LEIS has been used as a tool for high resolution nondestructive in-depth composition analysis of ultrathin layers [Brongersma et al., 2003] and shallow interfaces [Janssen et al., 2004]. 

Analysis by the Detection of Scattered Ions. Ions generally penetrate the specimen much less deeply than electrons of equivalent energy, so they are more surface-sensitive. Ion-based surface analytical techniques are popular because of their sensitivity and their ability, in some cases, to reveal the depth composition profile. 

In Figure 2 the positive ion intensities are plotted as a function of time for several major elements in the glass. These depth-composition profiles are compared for unleached and 30 minute aqueous leaching conditions. For each case, the results of profiles on two separate samples have been shown (solid and dashed lines), so that the reproducibility of the method can be judged. 

The Auger depth-composition profiles vapor-degreased surfaces and a "blank" surface are compared in Figures 8(a) and (b). Figure 8(b) shows that the small amount of chloride on the "blank" surface is a maximum at the outer surface and drops to undetectable as the film is penetrated 2 nm. By contrast, on the specimens exposed to vapor degreasing, the chloride concentration consistently reached a maximum 2 to 4 nm within the film. This increased level of chlorine in the film appeared to be related to a decrease in the ratio of iron to chromium oxides, particularly at the depth where the chlorine concentration was a maximum. 

Figure 8. Two depth composition profiles obtained by AES a 304 stainless steel surface exposed to commercial vapor degreasing, then exposed to atmosphere for 15Oo h (a), and a stainless steel surface as received (b). Key O (Xl) ...

Figure 9. XPS depth composition of an Inconel 600 alloy surface exposed to...

Figure 10. AES depth composition profile of an Incoloy 800 alloy surface oxidized at 550°C for...

Ion gun is used lor sample cleaning or for depth-composition analysis. 

Being essentially a surface technique, XPS valence band spectra also allows to monitor modifications occurring at the polymer surface during adsorption, reactions, of degradation... Very few contributions are, up to now, dealing with such studies ( ). The most direct use of the technique is actually a comparison of the core and valence photoelectron line intensities to deduce informations about the surface and the in-depth composition of the polymer, as well as about the orientation of the macromolecular chain at the surface boundary. 

SNMS In-depth Compositional Profiling of Plasma Coating... 

Figure 33.4 SNMS in-depth compositional profile of the TMS film deposited on (Ar -h H2) plasma pretreated steel, (a) atomic compositional profile, (b) profiles of atom clusters.

Fig. 3. (a) Steady-state depth composition profile of an originally crystalline silicon surface that has been exposed to a chlorine plasma, obtained from angle-resolved X-ray photoelectron spectroscopy, (b) Corresponding side-view schematics of near-surface atomic coordination left, 280-eV ions right, 40-eV ions. (From Layadi et al., 1997.)... 

The precise stoichiometry and orientation relationships of the silicides need not concern us further here, but it is crucially important to be aware of their presence and their influence on surface analytical investigations. Their formation has been carefully studied by AES combined with depth composition profiling [277, 280] and it was shown to be essential to follow the development of the Si peaks due to silicides at 88.5 and 95 eV. It is not sufficient to monitor only the main Au (69.5 eV) and Si(92eV) peaks to assess accurately the surface composition [278, 279], since this does not take account of compound formation. 

Unfortunately, the actual depth resolution can deteriorate a bit as a result of different effects, such as pulse mixing and signal taihng induced during aerosol transport, and will ultimately depend on the flow characteristics of the ablation cell and the data acquisition speed of the ICPMS unit used [25,45]. Moreover, the ratio between the depth penetration and the laser beam diameter must be kept below a critical value in order to obtain representative in-depth compositional data [43,46] thus, the use of larger beam diameters yields reliable information from deeper in the sample. 

Olla, M., Navarra, G., Elsener, B., Rossi, A. Nondestiuctive in-depth composition profile of oxy-hydroxide nanolayers on iron surfaces from ARXPS measuFemoit. Surf. Intaface Anal. 38, 964-974 (2006)... 

The surface and the in-depth composition of two different samples produced with low and high temperature sols, (LTS-1, HTS-1) were analysed X-Ray Photoelectron Spectroscopy (XPS) in order to get information on the chemical state of the different species and on their in-depth distribution. In particular, the goal of the investigation was to assess whether the Ag dopant was homogeneously distributed in the titania host matrix and in which chemical state (Ag° or Ag ) it occurred. 

In these three different mixed (binary and ternary) oxide systems, XPS and, in the case of the thin films, SIMS measurements provided eomplementary information on the surface and in-depth composition of the both as-prepared and ealeined speeimens, both as powders and thin films. 

As far as the surface and in-depth composition of the samples is concerned, the atomic percentages of the different chemical species as a function of the sputtering time are reported in the following Table 3.6. 

The actual surface and in-depth composition of the mixed oxide films (Ti02)o 6(Ta205)o 2 treated at 200°C and 800°C was studied by XPS. Figure 3.13 shows the survey spectra of the rutile film (Ti02)o6(Ta205)o.2 treated at 200°C (a) and at 800°C (b) after 30 min of sputtering, which demonstrates the presence of Ti and Ta for both films. 

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