bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of elastic photoelectron collisions in quantitative XPS
Authors: Jablonski A. , Ebel H. 
Published: May 2005

AbstractA fast Monte Carlo algorithm calculating the effects of elastic photoelectron collisions is presented. The algorithm is applicable to analyzer geometries with axial symmetry and with axis perpendicular to the surface (e.g. the CMA). The calculations were performed for four photoelectron lines: carbon 1s, aluminium 2s, cobalt 3p, and palladium 3d5/2. The following photoelectron characteristics were considered. (i) The angular distribution of photoelectrons leaving the surface. The distribution was found to follow the cosine distribution in practically all considered cases. Taking into account the elastic collisions did not change the shape of the distribution but decreased the photoelectron current leaving the surface, the difference increasing with atomic number of element. (ii) The distribution of emission depths of photoelectrons entering the analyzer. As a result of elastic collisions, more photoelectrons originate from the layer at the surface and less from the deeper layers. Thus, the actual depth of analysis is decreased. (iii) The total photoelectron current entering the analyzer. This current was also decreased by the elastic collisions. The difference reaches 1.6% for carbon 1s line, but increases to 16–19% for palladium 3d5/2 line. An elastic scattering correction in formalism of quantitative XPS is suggested. (iv) The average depth of analysis. This parameter was found to be most significantly affected by elastic scattering of photoelectrons. The depth of analysis was decreased by elastic collisions from 3–5% for carbon 1s line to 60–80% for palladium 3d5/2 line.
Effects of hydrogen on ISS analysis of dispersed metal catalysts
Authors: Diehl J. R. , Stencel J. M. , Spitler C. A. , Makovsky L. E. 
Published: May 2005

AbstractThe origin of inelastic scattering in ISS spectra at low energy ratios (E/E0 ≤ 0.3) is discussed, and a description of results from ISS and XPS experiments on well‐characterized Co/ZSM‐5 catalysts after calcination in air and reduction in H2, H2 + CO, or CO is given. These treatments show that the chemisorption of hydrogen on highly dispersed metallic Co and Fe causes shielding of the metal from ISS detection. Additionally, the presence of hydrogen, whether in a chemisorbed form or in other forms such as hydrocarbons or H2O, affects significantly the intensity of the inelastic scattering.
AES sputter profiling and angle resolved XPS of in situ grown very thin Tantalum‐oxide films
Authors: Mathieu H. J. , Landolt D. 
Published: May 2005

AbstractAngle resolved Auger electron spectroscopy (AES) and x‐ray photo‐electron spectroscopy (XPS) are compared to AES sputter depth profiling of ultra thin (<2 nm) Ta2O5 films to study their relative ability to determine thickness. Films were grown in situ by oxygen exposure after sputter claning the Tantalum‐metal surface. This way films between 2 L and 1800 L (1 L = 10−6 Torr s) were obtained. Results show that for such thin films the 50% oxygen amplitude criterion used to determine thickness cannot be applied anymore, because no steady state is reached in the film. On the other hand, angle resolved AES and XPS measurements show systematically higher values than data obtained by sputtering. However, since the former are critically dependent on the precision of the electron mean free path, λ, reasonable agreement can be obtained if one assumes an intermediate λ value between bulk oxide and metal; this can be justified by the presence of suboxides.
Crystalline effects in Auger electron spectroscopy
Authors: Bishop H. E. , Chornik B. , Legressus C. , Lemoel A. 
Published: May 2005

AbstractThe intensity of Auger emission is modified by the crystalline nature of the sample. One contribution to this effect is from the anistropic emission of the Auger electrons themselves but a second important contribution comes from changes in the surface ionization as a result of diffraction of the incident electron beam, (electron channelling). In practice the effects of anisotropic emission are often largely averaged out over the input aperture of the electron analyser but the contribution from electron channelling is not averaged and can be large. For instance there can be up to a three‐fold variation in the intensity of the KLL peak of aluminium when the incident beam is rotated ±5° about the [110] direction. Experimental measurements showing the magnitude of crystallographic effects in an Auger spectrometer (ESCALAB II, V.G.Scientific Ltd) are presented for polycrystalline copper and silver samples and for single crystals of aluminium and magnesium oxide. The channelling contrast can be explained qualitatively in terms of the two beam theory of electron diffraction but a multiple beam treatment is necessary to give a quantitative description of the effect.
A comparative study of SIMS depth profiling of boron in silicon
Authors: Clegg J. B. , Morgan A. E. , de Grefte H. A. M. , Simondet F. , Huber A. , Blackmore G. , Dowsett M. G. , Sykes D. E. , Magee C. W. , Deline V. R. 
Published: May 2005

AbstractDetails are given of a round robin depth profile comparison between 9 SIMS instruments (6 instrument types) applied to the analysis of an ion implanted Si(B) sample. It is shown that the shape of the boron profile is not sensitive to the sputter conditions employed and that the profile width data shows agreement to within 10% over the concentration range ∼1021 to 1015 cm−3 (104 to 0.02 ppma). This level of agreement is encouraging and gives confidence in the reliability of the SIMS method. Instrumental factors which control the profile dynamic range are shown to be dependent on the system configuration. With the quadrupole‐based raster scanning instruments the quality of the primary beam is of importance, while with the imaging ion microscope systems, memory effects are significant. A dynamic range of ∼5 × 105 is obtained from both types of instrument. The analysis of identical samples prepared by ion implantation should enable other SIMS workers to check instrumental performance.
The effect of surface topography evolution on sputter profiling depth resolution in Si
Authors: Carter G. , Nobes M. J. , Lewis G. W. , Brown C. R. 
Published: May 2005

AbstractExperimental studies of the development of surface topography on Si surfaces during Ar+ ion bombardment and sputter erosion indicates that the Si becomes continuously prismatically facetted and that facet dimensions increase linearly with mean eroded depth. These observations lead to an analytic model of the achievable depth resolution δz/z0 in sputter erosion which is independent, for deep profiles of z0.
Suppression of molecular ions in SIMS spectra of metals and semiconductors
Authors: McIntyre N. S. , Fichter D. , Metson J. B. , Robinson W. H. , Chauvin W. J. 
Published: May 2005

AbstractStrong suppression of molecular ions in positive secondary ion mass spectra (SIMS) is achieved by electric isolation of a specimen (SI) with an electrically charged aperture situated immediately above its surface. This technique is also useful for controlling the surface charging on an insulator. The origin of this phenomenon has been explored using metals and semiconductors as models. The strong molecular suppression effect is found to result from the very high ion kinetic energies (>400 eV) emerging from the surface under SI conditions. The charged aperture is believed to stabilize surface charging by confining it within a small region. SI methods for reducing molecular ions in silicon and mild steel specimens reduce major molecular fragments by 3–4 orders of magnitude.
The energy dependence of electron attenuation lengths
Authors: Powell C. J. 
Published: May 2005

AbstractAn analysis has been made of electron attenuation length data for nine materials in terms of the Bethe theory for inelastic scattering in matter. It was found that the Bethe equation adequately described the energy dependence of the data in all materials over the typical range 100–1500 eV. The Bethe equation appears to be superior to the empirical relation proposed by Wagner, Davis, and Riggs (1980).
The relationship between electron and ion induced secondary electron imaging: A review with new experimental observations
Authors: Lai S. Y. , Brown A. , Vickerman J. C. , Briggs D. 
Published: May 2005

AbstractThe phenomenalogical and theoretical aspects of secondary electron emission due to ion bombardment in the keV energy range has been reviewed and a comparision of this process with secondary electron emission due to electron bombardment has been made. The similarities and differences between the contrasts in the secondary electron images of test specimens studied with both scanning microfocused Ga+ beams and electron beams have been explained by the mechanisms of the secondary electron emission processes. From ion induced secondary electron images information on the topography, material and crystallographic nature of specimens can be obtained with high surface sensitivity. Differences in surface potential on different areas of a specimen has also been shown to result in voltage contrast effects.
Application of XPS to the characterization of polymer‐loaded drugs
Authors: Garbassi Fabio , Carli Fabio 
Published: May 2005

AbstractSeveral drug‐polymer systems have been investigated by XPS can contribute to solve questions like the mechanism of drug loading on the polymeric support and the effectiveness of the packaging system against the action of humidity. The reliability of the quantitative surface analysis and the applicability to a variety of systems has been also checked.
Scanning acoustic microscopy
Authors: Balk Ludwig Josef 
Published: May 2005

AbstractGeneration and propagation of sound and ultrasound in materials are strongly affected by various quantities such as elastic and thermal, electronic and magnetic properties. Accordingly, local changes of one of these quantities can give information on the physical and chemical nature of that region which the acoustic signal is generated in or in which the propagation occurs. Based on this, different techniques of ‘scanning acoustic microscopy’ have been developed, important methods in this respect being conventional scanning acoustic microscopy (CSAM), scanning photo‐ or laser acoustic microscopy (SPAM) and scanning electron acoustic microscopy (SEAM). In CSAM ultrasound is focused onto the specimen surface, then its transmission or reflexion within the specimen is determined. Thus propagative properties and acoustic scattering are dominant in CSAM. In SPAM and SEAM a focused laser or electron beam, mostly intensity‐modulated with time, is used to generate an acoustic signal within the probed surface region. Recently these two techniques have been accompanied by the introduction of scanning ion acoustic microscopy (SIAM), which uses a focused ion beam for sound generation. In these three techniques the sound generation mechanism is the main source of information, as typical operation frequencies are low compared to CSAM and quite often very long acoustic wavelengths are resulting. However, for a detailed analysis of the acoustic image contrast, contributions of acoustic propagation to the signal have to be taken into account, too. Due to the different mechanisms involved in signal formation, the mentioned techniques allow determination of a large variety of material parameters, and they are not only competing methods, but add up to a complete set of techniques for material microcharacterization. The applicability of these methods, their advantage and disadvantages are discussed.
Simultaneous analysis of fracture surfaces by auger and energy dispersive x‐ray mapping
Authors: Wirth A. , Andreoni I. , Gregory G. 
Published: May 2005

AbstractThe grain boundary segregation of the metalloid impurities antimony and phosphorus to the prior austenite grain boundaries of an Fe‐3.5 Ni‐1Cr alloy during embrittlement at 430°C has been studied by simultaneous Auger and energy dispersive x‐ray analysis. The segregating species were found to be related to the tempering characteristics of the unembrittled microstructures. Initial intergranular embrittlement in a quenched and tempered martensite microstructure was associated with the prescence of phsophorus whereas the initial embrittlement in a bainitic microstructure was associated with the segregation of antimony. The difference in behaviour between the two microstructures has been explained in terms of site competition at the grain boundaries. In the case of the tempered martensite microstructure the carbon activity is reduced as a consequence of the formation of chromium rich precipitates at the grain boundary. Carbon activity is reduced as a consequence of the formation of chromium rich precipitates at the grain boundary. The reduction in carbon activity allowed phosphorus migration to the boundary producing intergranular embrittlement. In bainites the predominant precipitate M3C increased the carbon activity with a resultant decrease in phosphorus concentration the grain boundary and the absence of intergranular failure in the early stages of embrittlement. Prolonged embrittlement of the bainites produced a low energy intergranular failure. Increased nickel and antimony concentrations at the grain boundaries were associated with the formation of a fine grain boundary precipitate low in chromium. The increased carbon activity continued to prevent appreciable phosphorus segregation but was not sufficient to inhibit the cosegregation of nickel and antimony.
An AES (SAM), ESCA and ISS study of the oxidation of Pt3/Sn. 1: low pressure exposure to o2
Authors: Hoflund Gar B. , Asbury Douglas A. , Kirszensztejn Piotr , Laitinen Herbert A. 
Published: May 2005

AbstractESCA, ISS, AES and scanning Auger microscopy have been used to examine a sputter‐cleaned Pt3Sn alloy surface before and after exposure to oxygen at 10−6 Torr. It is found that the amount of oxygen adsorbed on a sputtered surface is a strong function of sample temperature with a maximum at about 200°C. The clean surface consists of regions of varying Pt‐to‐Sn concentration ratios. Regions near grain boundaries are tin rich, and the tin concentration decreases in moving away from a grain boundary until a platinum‐rich region is reached. ESCA shows that an exposure to oxygen causes oxidation of the tin but no change in the Pt core‐level features. ISS shows that segregation of tin to the surface occurs and that the surface Pt concentration decreases due to coverage by the tin.
AES and SIMS of carbonaceous adsorbate layers on Pt, Rh, and PtRh
Authors: van Langeveld A. D. , Niemantsverdriet J. W. 
Published: May 2005

AbstractCarbonaceous adsorbate layers on polycrystalline Pt, Rh, and PtRh, formed from C2H4 at different temperatures, have been investigated by AES and SIMS. Information on the properties of the carbon has been derived from the fine structure of the carbon Auger peak. SIMS spectra of positive and negative ions in the 12–26 mass range exhibit great sensitivity for the nature of the carbonaceous deposits and reveal the influence of the substrate. Auger spectra indicate that Pt segregates to the surface of the clean PtRh alloy.
Surface segregation and oxidation studies of AlBe alloys
Authors: Ahmad M. , Blakely J. M. 
Published: May 2005

AbstractSurface segregation and oxidation of AlBe alloys have been studied using the LEED‐AES technique. Results obtained from one polycrystalline sample and three single crystals with (001), (011) and (111) orientations show no segregation of Be to the clean Al surface. The annealing temperatures ranged from 300 °C to 600 °C for a few minutes to a few hours. Results from the polycrystalline sample suggest that in the presence of oxygen or Al2O3 on the surface, Be diffuses to the surface during annealing (at 400 °C or above) to form BeO and reduces Al2O3. The difference in the free energies of formation of the bulk BeO and Al2O3 favors this reaction. A one‐to‐one correspondence has been found between the surface coverage of BeO formed to that of Al2O3 present prior to annealing the sample. The three single crystals had much less Be in the bulk and this affects the reduction reaction by limiting the rate of Be diffusion to the surface. LEED investigation for the (111) oriented crystal showed that BeO grows as the (0001) basal plane on the Al(111) surface. The magnitude of the misfit between unrelaxed Al(111) and BeO(0001) as measured from the relative positions of superlattice beams indicate some compression or expansion in the interface region.
Modeling the effect of ion mixing and surface roughening on depth profiles
Authors: Tompkins Harland G. 
Published: May 2005

AbstractA simple instrument transfer function is proposed to convolute hypothesized profiles (e.g. sharp interfaces). The convoluted profiles can then be compared to measured profiles. The convolution involves an ion mixing factor which has a constant value independent of the sputter depth and a roughening factor which is a fixed fraction of the sputter depth. Electron escape depth is also included in the convolution. Measured profiles for silicon dioxide films varying form 23 to 1000 angstroms were obtained with AES and argon ion sputtering, and are compared to the convoluted hypothesized profiles. An ion mixing factor of 10 angstroms and a roughening factor of 1% of the sputter depth were obtained. This roughness factor is significantly lower than usually obtained for many other materials, e.g. metal films.
An AES study of the oxidation of polycrystalline zirconium at room temperature and low oxygen pressures
Authors: Sanz J. M. , Palacio C. , Casas Y. , Martinez‐Duart J. M. 
Published: May 2005

AbstractAuger electron spectroscopy has been used to characterize the oxidation of polycrystalline zirconium in an oxygen atmosphere at low pressures (10−8 ≤ P ≤ 10−5 Torr) and room temperature after cleaning the surface by Ar+ ‐ion bombardment. Quantitative analysis of the oxidation process was performed by using the intensity of the Zr(M45N23N45) line which is characteristic of the metallic zirconium. It is concluded from this work that oxidation proceeds as follows: (i) dissociative chemisorption for oxygen exposures lower than 2 L; (ii) formation of nuclei of oxide which grow until coalescence for exposures between 2 and 60 L; (iii) thickening of the oxide film grown in the previous stage. A limiting thickness of 1.5–2 nm is estimated.
Suppression of surface topography development in ion‐milling of semiconductors
Authors: Bulle‐Lieuwma C. W. T. , Zalm P. C. 
Published: May 2005

AbstractThe occurrence and growth of hummocks on semiconductor surfaces rotated during ion bombardment have been studied. A simple geometrical is proposed which explains why such topographical features may be observed at incident angles of about 65° with respect to the surface normal, whereas they disappear or do not develop at angles of about 80°. It is argued that even microscopic surface undulations with dimensions of the order of 10 nm initiate hummock formation. Finally it is shown that a smooth surface, which can be produced by ion‐milling at grazing incidence, effectively prevents surface tropography development at any angle of incidence.
An X‐ray photoelectron spectroscopic study of a nitric acid/argon ion cleaned uranium metal surface at elevated temperature
Authors: Paul Alan J. , Sherwood Peter M. A. 
Published: May 2005

AbstractX‐ray photoelectron spectroscopy has been used to study the surface of uranium metal cleaned by nitric acid treatment and argon ion etching, followed by heating in a high vacuum. The surface is shown to contain UO2−x species over the entire temperature range studied. Heating to temperatures in the range 400–600°C generates a mixture of this oxide, the metal and a carbide and/or oxycarbide species.
Structural properties of native and ultra thin thermal oxides of silicon as studied by SEXAFS
Authors: Braun W. , Bader M. , Holub‐Krappe E. , Haase J. , Eichinger P. 
Published: May 2005

AbstractThe geometrical structure of native silicon oxide and ultra thin thermal silicon oxides grown in situ on a Si(100) wafer have been investigated by surface extended x‐ray absorption fine structure (SEXAFS) above the oxygen K absorption edge (∼530 eV). The SiO bond length of the native oxide is identical with that of α‐quartz and amorphous silica and the SiO bond length of the thermal oxides corresponds closely to that of β‐quartz which is the medium temperature modification of α‐quartz.
Backscattering correction factor for AuCu alloys in quantitative Auger analysis
Authors: Ze‐jun Ding , Shimizu Ryuichi , Ichimura Shingo 
Published: May 2005

AbstractThe backscattering factor R, which corrects matrix effects in quantitative AES analysis, was obtained from Monte Carlo calculations for the AuCu alloy system being proposed as test standard samples for quantitative surface chemical analysis. The Monte Carlo algorithm is based on the combined use of the Gryzinski's excitation function with the Bethe's stopping power for inelastic scattering and elastic scattering cross section obtained by partial wave expansion method. The calculation of R for 5 keV and 10 keV electrons at angles of incidence 0° and 45° lead to the functional representation R(Z, U) = A(Z)UB(Z) + C(Z), where Z is the mean atomic number of the sample and U the ratio of the primary energy to the binding energy. This representation describes the calculated R values within the maximum error 2%.
A mixed X‐ray source for XPS and X‐AES
Authors: Xiang‐rong Yu 
Published: May 2005

AbstractThe concept of the Auger Parameter (AP) is becoming increasingly important in XPS–X‐AES (x‐ray photoelectron spectroscopy and x‐ray‐excited Auger electron spectroscopy). The advantages and disadvantages of present usable monochromatic and unmonochromatic x‐ray sources for determination of the AP are considered. A novel anode face pattern for the generation of mixed x‐ray radiations to obtain the optimum photo‐ and Auger electron lines simultaneously without suffering from the charging effects caused by different x‐ray sources is suggested.
Depth profiling of shallow arsenic implants in silicon using SIMS
Authors: Clegg J. B. 
Published: May 2005

AbstractThe analytical conditions necessary for the accurate measurement of shallow As implant profiles in crystalline Si have been critically evaluated. It is shown that near‐normal oxygen bombardment (θ = 2°) gives rise to a drive‐in of the As peak toegether with an enlarged exponential tail due to segregation processes associated with SiO2 formation in the near‐surface region. At θ = 45°, both effects are greatly reduced. Thus, for enhanced depth resolution, it is essential to use oblique bombardment with low probe energies. Silicon sputter yield variations in the pre‐equilibrium region are shown to be much smaller with θ = 45° and the differential peak shift amounts to only 0.6 nm per keV O+ compared with 3.0 nm at θ = 2°. The oblique sputter conditions do, however, lead to an increase in the thickness (w) of the pre‐equilibrium region together with a loss in analytical sensitvity. The use of an oxygen jet is shown to reduce w to about 1 nm but gives rise to ‘chemically induced’ profile tailing with low energy (5 keV) As implants. Systematic measurements with different probe energies (1 and 2 keV O2+) show that As implants down to 10 keV are reliably profiled with θ = 45°. Comparison of our As range data with published Rutherford backscattering spectrometry values shows good agreement for the standard deviation while the mean projected range shows a systematic difference of ≃ 10%.