Determination Of Concentration Depth Profiles Research Articles

Surface and Thin Film Analysis with Electron and Mass Spectrometric Techniques

We give a short overview of recent analytical techniques for compositional surface analysis and the determination of concentration depth profiles. More specifically, the principle, the instrumentation and the performance of the routinely used electron spectroscopic and mass spectrometric methods, namely Photo- and Auger Electron Spectroscopy PES and AES, resp. Secondary Ion and Secondary Neutral Mass Spectrometry SIMS and SNMS, are described. The application of these techniques to the analysis of thin film structures is demonstrated by corresponding practical examples. The potentialities of the different techniques are specifically addressed with regard to the quantitation of the measured data, detection limits for trace analysis as well as the spatial resolution both in directions parallel and perpendicular to the sample surface.

Anomalous diffusion of iodine ions into polypropylene implanted with F+ and I+ ions

AbstractThe diffusion of K and I atoms from 5 M water solution of KI into polypropylene implanted with 150 keV F+ and I+ was studied at boiling temperature. Standard Rutherford back scattering (RSB) technique was used for the determination of concentration depth profiles of diffused atoms. It was found that the I and K atoms penetrate the polymer surface layer affected by ion implantation and they are captured by trapping centers produced by electronic energy losses of implanted ions. The uptake of K atoms is several times higher than that of I atoms, and the relative K concentration exceeds the KI stoichiometric value. © 1995 John Wiley & Sons, Inc.

A New Technique for Depth Profiling on a Nanometer Scale

AbstractA new technique is presented for the determination of concentration depth profiles. Surface atoms are sputtered by an ion beam and deposited on a clean silicon wafer. The wafer is rotated behind a slit in step with the sputtering progress. In this way the depth profile of the sample is transferred into a lateral distribution of the sputtered atoms on the target wafer. Subsequently the wafer is scanned by Total Reflection X-ray Fluorescence Spectrometry (TXRF) which is capable of detecting traces of metallic impurities on wafers down to 10-4 of an atomic monolayer. The sequence of ion-beam sputtering, deposition of the sputtered atoms and TXRF analysis results in an excellent depth resolution in the case of areal structures. Using an ion source of the Kaufmann type, an extrapolated perpendicular resolution better than 0.1 nm was obtained for a 1500 mm2 surface. For a surface area of 3 mm2 a depth resolution of 1 nm is expected. 1.4 nm was actually measured to be the width of a coherent Ti/Al-interface within a layered structure.

Anomalous diffusion of Pb atoms into polyethylene implanted with F +and As + ions to different doses

The diffusion of Pb atoms from a 0.5M aqueous solution of lead acetate into polyethylene (PE) implanted with 150 keV F + and As + ions to different doses was studied at room and boiling temperatures. The standard Rutherford backscattering (RBS) technique was used for the determination of concentration depth profiles of incorporated atoms. Pb diffusion in the pristine polymer proceeds according to the common Fickian law with diffusion coefficients of 1.5 × 10 −16 cm 2s −1 and D = 5.3 × 10 −14 cm 2 s −1 at room and boiling temperatures, respectively. Anomalous diffusion of Pb atoms was observed into the PE implanted to ion doses below 5 × 10 14 cm −2. In these cases a pronounced diffusion-capturing mechanism takes place with the Pb atoms being captured on trapping centres produced by electronic energy losses of implanted ions. For implanted doses above 5 × 10 14cm −2, nearly Fickian diffusion is again observed with diffusion coefficients close to those of pristine material. Strongly reduced Pb incorporation in specimens implanted to higher doses is explained by structural changes of the polymer surface layer.

Determination of concentration depth-profiles by angle-dependent XPS and AES data

Determination of concentration depth-profiles by angle-dependent XPS and AES data

Determination of concentration depth profiles by spark source mass spectroscopy

SSMS in-depth analysis was used to study diffusion profiles of Be in Cu, which extend over some millimeters. The calculated diffusion coefficients agree well with values measured on the same samples by both lateral SSMS and SIMS.

Identification of atomically sharp concentration steps in solids

Controlled sputter removal of a solid in conjunction with one of the recent methods for surface analysis has become the most sensitive technique for the determination of concentration depth profiles and concentration transitions at thin film interfaces [1]. As microsectioning by sputtering occurs at an atomic scale, and as the information depth of the mass spectrometric techniques SNMS and SIMS or of Auger electron spectroscopy AES for appropriate Auger peaks is confined to the first or the first two outermost atomic layers, the identification of atomically sharp concentration steps should be possible in principle. Even when minimizing all interfering instrumental influences (for a recent review see [2]), there exist, however, several physical processes of fundamental nature which cause residual broadening effects in high resolution sputter depth profiling. These processes are always connected with the sputtering mechanism. Their origin and their influences are briefly discussed in the following.

Concentration depth profiling in fluorine implanted iron

Laminated iron foils have been implanted with 50 keV fluorine ions at different doses between 2×10 16 ions/cm 2 and 2×10 17 ions/cm 2. Nuclear resonant reactions are used for the determination of concentration depth profiles. Gamma rays from the 19F(p, αγ) 16O ∗ reaction are detected and the advantage of low energy resonances is demonstrated, namely the 340.46 keV resonance has the advantage of high sensitivity and low background making possible large depth investigations (2500 Å). Diffrent effects are investigated: surface roughness, total dose, stopping power, thermal diffusion, corrosion, … Samples are treated at different temperatures between 100 and 450°C, the diffusion of fluorine is observed with the 340.46 keV resonance, the sensitivity is good and the background is very low. Above 450°C a rapid oxidation of the surface is observed by nuclear resonant scattering. Depth profile measurements indicate that the oxidation process is responsible for migration of the fluorine ions.