bluuebunny/crossref_metadata_2025 huggingface dataset:
Crystalline effects in Auger electron spectroscopy
Authors: Bishop H. E. , Chornik B. , Legressus C. , Lemoel A.
Published: May 2005

The 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

Details 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

Experimental 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

Strong 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

An 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

The 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

Several 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

Generation 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

The 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

ESCA, 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

Carbonaceous 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

Surface 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

A 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

Auger 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

The 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

X‐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

The 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

The 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

The 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

The 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%.
A SIMS calibration exercise using multi‐element (Cr, Fe and Zn) implanted GaAs
Authors: Clegg J. B. , Gale I. G. , Blackmore G. , Dowsett M. G. , McPhail D. S. , Spiller G. D. T. , Sykes D. E.
Published: May 2005

Multi‐element (52Cr, 56Fe and 66Zn) implanted GaAs samples have been prepared specially for SIMS calibration. Absolute chemical measurements gave retained ion doses which agreed to within 12% of the nominal implanted dose (2.0 × 1014 atoms cm−2). Comparative SIMS depth profiles with five instruments gave Cr mode depth data which showed a variability of 5%. After data normalization to a common mode depth (168 nm) the shape of all profiles showed good agreement. SIMS anàlysis of similar samples containing lower dose implants (1.0 × 1013 atoms cm−2) showed that ∼50% of the Cr was contained in the near surface region (0–0.03 μm). This surface peak was not observed in profiles of samples which had been singly implanted with Cr. It is proposed that the Cr surface peak results from radiation enhanced out‐diffusion initiated by the subsequent Fe implant. Whilst the high dose multi‐implant samples showed a similar Cr surface accumulation, its magnitude in relation to the ion implanted dose, was smaller. These samples therefore form reliable calibration specimens for the simultaneous determination of the secondary ion responses of Cr, Fe and Zn in GaAs.
The energy dependence of electron inelastic mean free paths
Authors: Powell C. J.
Published: May 2005

An analysis has been made of the dependence on electron energy of calculated inelastic mean free paths (IMFPs) for aluminum, copper, silver, and gold from four recent sources of data. The analysis was made using Fano plots which clearly show differences in energy dependences. In addition, the slopes of linear regions in the Fano plots can be compared with values calculated from experimental optical data and with values obtained from Fano plots made with experimental attenuation length (AL) data. It was found that the slopes of the Fano plots using IMFPs from calculations of Powell and Penn agreed well with the optical results; there was generally good agreement for the IMFPs of Ashley et al., but the slopes using the IMFP data of Szajman et al. exceeded the optical values by 9–40%. The slopes in the Fano plots using AL data for Al, Cu, and Au exceeded the optical values by 29–54 %; this result is similar to those found in other analyses and indicates that the electron energies for these AL measurements were not high enough to be in the asymptotic Bethe region. Analysis of the optical data also showed that a lower limit for the electron energy range over which the Fano plots could be expected to be linear (with their asymptotic slopes) was about 400 eV for Al and about 1000 eV for Cu, Ag, and Au. More extensive AL measurements over a wide electron energy range are needed to determine the shapes of the Fano plots for different types of materials.
The inelastic mean free paths of electrons in semiconducting III–V compounds
Authors: Kwei C. M. , Chen L. W.
Published: May 2005

The inelastic mean free path of electrons in solids is an important parameter in surface studies using AES and XPS. In this paper we present theoretical calculations of this parameter for the semiconducting III‐V compounds GaAs, GaSb, GaP, InSb and InAs. These calculations are based on a model dielectric function for the response of the valence band and the local‐plasma‐approximation for the response of inner shells. In the former case, the Kramers–Kronig relation and the partial sum rule for valence electrons are applied. In the latter case, the electron density distribution obtained from the Hartree–Slater model is utilized. Results are compared to other calculations using the Penn's model and the model of Ashley et al. for GaAs. Since no data on experimental electron attenuation lengths in the important semiconducting III–V compounds are available, it is suggested that direct calculations of the present type are useful in applications.
Concept of an imaging XPS system
Authors: Seah M. P. , Smith G. C.
Published: May 2005

The concept of an imaging XPS system is analysed and the various approaches discussed. For instrument and design flexibility it is shown that a standard XPS system with an efficient input lens can be used to form a virtual image of the spectrometer input aperture on the sample surface. This defined area of analysis may be rastered across the sample surface using a pre‐lens scanning deflector system. In this way good XPS images of 256 × 256 pixels and of 250 μm resolution over an area of diameter 10 mm may be formed in ten minutes. Examples are provided from components for the electronics assembly industry demonstrating that insulators cause no problems. Design considerations are then detailed for optimizing imaging XPS systems at 25 μm and 10 μm spatial resolution involving pre‐lens scanning systems and position‐sensitive detectors.
The spectral background in electron excited Auger electron spectroscopy
Authors: Matthew J. A. D. , Prutton M. , El Gomati M. M. , Peacock D. C.
Published: May 2005

The power law form of the secondary electron cascade from electron bombarded solids first suggested by Sickafus is explored both theoretically and experimentally. Backgrounds of the form AE−m are shown to result from a range of different theoretical models of the electron‐solid interaction in which generation of fast secondaries by electron Compton scattering and transport to the surface are treated separately. The precise value of the exponent m is seen to depend upon the balance between elastic scattering strength and the energy dependence of the inelastic mean free path.

The experimental results for eight different samples with atomic numbers between 6 and 78 are reported. The constant A appears to be related to the number density of valence band electrons. The values of m fall within the range predicted by the theoretical arguments. The generality of the form AE−m to many materials is useful for the estimation of both the Auger back‐scattering co‐efficient and the energy dependence of the inelastic mean free path from measurement of the parameters A and m.
A new method of spectra acquisition and exact mass determination of resolved peaks in high mass resolution ion microscopy
Authors: Thorne N. A. , Degrève F.
Published: May 2005

A major problem in high resolution mass spectrometry of solid materials has been the difficulty or even the impossibility associated with identifying the resolved peaks, i.e. the determination of their exact mass. A method of exact mass determination (relative precision in the range of 10−5) of resolved peaks is presented which requires no foreknowledge of the specimen. The method is derived from mass spectrometry techniques commonly employed for the analysis of liquid or gaseous organic samples, and is based on three steps: (1) the use of an external reference sample; (2) sequential analysis of the reference and unknown sample; and (3) superposition of the two spectra. The technique is illustrated using a standard CAMECA IMS 3f ion microscope.

A further advance has been the development of single ion sensitive mass spectrography, where the entire spectrum within a narrow mass range is simultaneously viewed in real time. Spectra acquisition times are reduced by a factor of up to ten. Mass spectrography allows the detection of transient peaks or peaks of rapidly varying intensity, e.g. thin surface films or oxides. Using an image processor the spectra may be integrated or averaged in real time before storing in memory. Real time spectra acquisition and interpretation make high mass resolution SIMS (indispensable in material science) a routine operation providing information otherwise difficult or impossible to obtain.
Analysis of polymer surfaces by SIMS. 12. On the fragmentation of acrylic and methacrylic homopolymers and the interpretation of their positive and negative ion spectra
Authors: Hearn M. J. , Briggs D.
Published: May 2005

The positive and negative ion spectra from homologous series of alkyl methacrylate, hydroxyalkyl methacrylate and alkyl acrylate polymers; poly (methacrylic acid) and poly(methacrylic anhydride) are reported. A systematic interpretation of the spectra can be accomplished on the basis of fragmentation pathways consistent with the known effects of other ionizing radiations. The negative ion spectra, previously little studied, are a powerful probe of structure for this class of polymer.
The influence of oxygen on the thermal mixing of Cr and GdxOy thin films
Authors: Shanker Kartik , MacDonald Jack R. , Chan T. C.
Published: May 2005

Thin films of Cr and Gd oxide were sequentially deposited on Kapton H polyimide and heat treated in vacuum or air at 550–673 K. The interactions between the layers was followed with Auger electron spectroscopy and Rutherford back‐scattering spectrometry. Heating caused the Cr oxide thickness to grow as a function of thermal exposure. No intermixing occurred between the Cr and GdxOy layers until the presence of O in the Cr layer near the interface. Rapid diffusion of Cr oxide into the Gd oxide layer then occurred. The Gd/O Auger signal ratio increased on heating when the Cr film thickness was small, but remained unaffected with thicker Cr films. There was no diffusion of Gd into the Cr overlayer. Diffusion of GdxOy into the polyimide was observed. A thin Cr underlayer acted as a barrier to such diffusion, but possibly only till its oxidation. Irrespective of the compositional changes, heating increased the tensile stress of the films; they also showed a greater susceptibility to tearing. The films became progressively darker, eventually turning chocolate brown. They retained their metallic lustre much longer, until the oxidation of the Cr film.
Ion bombardment effects on the near‐surface composition during sputter profiling
Authors: Lam N. Q.
Published: May 2005

The alteration of the near‐surface composition that has often been observed in ion bombarded alloys and compounds results from the dynamic interplay of several processes. In addition to displacement mixing leading to a randomization of atomic locations, which is dominant at relatively low temperatures, and preferential loss of alloying elements by sputtering, many thermally‐activated processes, including radiation‐enhanced diffusion, radiation‐induced segregation and Gibbsian adsorption, also play important roles. The relative significance of each process in the evolution of the sputtered flux composition and of the compositional profile of the target depends on the type of alloys, temperature and ion characteristics. Although a good semi‐quantitative understanding already exists for most of the individual processes, the number of systematic investigations of alloy sputtering that consider all of these processes and their potential interactions is still rather limited. A fundamental understanding of the synergistic effects of these processes is, however, essential for quantitative analysis of multicomponent‐material surfaces, since sputtering is routinely applied in conjunction with various analytical techniques to depth‐profile the composition. The purpose of this paper is to characterize the processes in simple physical terms and to point out under what conditions they may become important for compositional changes in near‐surface regions of sputtered alloys, based on selected results of recent model calculations and experimental studies.
Simulation of the LMM auger spectra of copper
Authors: Dubot P. , Jousset D. , Pinet V. , Pellerin F. , Langeron J. P.
Published: May 2005

Quantitative Auger analysis is much more difficult to achieve than quantitative XPS, as the latter shows only one photoelectron peak when the former exhibits many relaxation peaks laying over a 100 ev range. A good way to check our understanding of the Auger process is to simulate spectra. For that we need to get an estimation of (i) the ionization probability and its variation with depth, (ii) the contribution of each ionization and relaxation processes, and (iii) the type of interaction between electron and solid. As the phenomena are basically the same for the transport of Auger electrons as for primary electrons, we used the same physical parameters and simulation models (layer by layer and Monte Carlo) as we previously used for the determination of the background in copper. A comparison between calculated and experimental results is presented.
Quantitative AES: The establishment of a standard reference spectrum for the accurate determination of spectrometer transmission functions
Authors: Smith G. C. , Seah M. P.
Published: May 2005

The precise shape of the whole electron spectrum in AES is defined by (i) the physics of the process, and (ii) the intensity/energy transmission function of the measurement system. In many systems item (ii) is uncharacterized and surveys show variable effects of over an order of magnitude. This gives rise to equivalent errors in quantitative AES where published data banks are used and the spectrometers are uncalibrated.

In this study we consider both the process and the measurement system, and show how the parameters of each may be measured and how each affects the final measured spectrum in the direct mode. The factors considered include the orientation of both the incident and emitted electrons, and the energy dependence of the transmissivities of the spectrometer and the detection system. Detailed measurements of high accuracy for a copper reference sample show the extent to which the reference procedures may be followed and equivalent data be recorded from different instruments.
An engery‐resolved electron stimulated desorption (ESD) study of oxygen‐exposed Ag (110)
Authors: Corallo Gregory R. , Hoflund Gar B. , Outlaw Ronald A.
Published: May 2005

Energy‐resolved ESD data obtained from Ag(110) after exposure to oxygen at room temperature are presented. The oxygen is found to desorb predominantly as a hydroxyl species. The surface hydrogen apparently originates from the bulk silver and is only removed slowly over many sample anneals. OH+ desorbs with an energy of 4.7 eV, and H+ desorbs with an energy of 3.0 eV. The results suggest that oxygen adsorbs at two or more different bonding sites on this surface. OH+ desorbs by ESD from the most prevalent of these sites, and O+ desorbs from another site which seems to fill first upon oxygen exposure. The primary beam energy is an important ESD variable since exciting the Ag 3d core levels results in a substantial reduction in the OH+ desorption yield.
Surface reactions during rapid solidification and handling of Al5Mn2.5Cr powders
Authors: Olefjord I. , Nylund A.
Published: May 2005

Rapidly solidified Al powders were analysed in the as‐received condition, and after exposure in humid atmospheres, using ESCA and Auger spectroscopy. The composition of the powder is Al5Mn2.5Cr. It was produced by the ultra sonic gas atomization (USGA) technique. The cooling rate was in the range 105–106 K s−1.

The surface of the as‐atomized powder is partly covered by aluminium oxide particles formed at high temperatures during atomization and by a thin uniform oxide film formed between the oxide particles. The thin film is formed at low temperatures during atomization and during handling of the powder. The average thickness of the oxide is 50 Å.

The powders were exposed in humid atmosphere at 22°C for 1 day and for 1 week, at relative humidities of 60% and 80%. During the exposure, aluminium hydroxide is formed on the surface of the oxide. The thickness of the hydroxide layer increases with exposure time and the humidity. After exposure for 1 week in relative humidities of 60% and 80% the thicknesses of the hydroxide layers were 10 and 12 Å, respectively.
Surface characterization of AISI 304L stainless steel subjected to various prebonding treatments. Correlation with adhesion measurements
Authors: Gaillard F. , Romand M.
Published: May 2005

In order to promote strong and durable steel/epoxy adhesive joints, various stainless steel surface treatments are investigated. The adherend surface characterization is achieved by both spectroscopic (low energy electron‐induced x‐ray spectrometry (LEEIXS), AES, XPS) and microscopic (SEM) techniques. The strength of the steel/epoxy bonds is evaluated, after bonded sample ageing under hydrothermal conditions (70°C, 95% r.h.), by means of a mechanical three‐point flexure test, sensitive to the interfacial properties of the bonded systems.

The stainless steel surface treatments used in this study include conventional ones, such as solvent degreasing, acid etching, and phosphating and more original ones such as anodizing in sulphuric‐chromic or nitric acid electrolytes. These two last treatments lead to the formation of a ‘thick’ (in the range 10 to 90 nm) surface layer, highly chromium (as Cr(III))‐enriched, as determined by LEEIXS and XPS.

The anodized stainless steel/epoxy systems exhibit performances which largely outclass those allowed by conventional steel prebonding treatments. These performances are very dependent upon the electrochemical conditions (current density, treatment duration, electrolyte temperature and composition) chosen for the anodizing process.
The application of surface analysis to studies of the environmental degradation of polymer‐to‐metal adhesion
Authors: Watts J. F.
Published: May 2005

The use of surface analysis in adhesion studies is reviewed and the various levels of information attainable is illustrated with a series of examples taken from studies of organic coatings on steel substrates. It is concluded that for a complete understanding of environmental degradation processes the intact interfacial bond must first be will understood, and failure in an inert atmosphere carefully documented.
Analysis of ion implanted ceramics. Studies of iron implanted MgO and Al2O3
Authors: Marest G.
Published: May 2005

The effects due to ion implantation in ceramics depend on different factors: nature of the material, beam parameters and also substrate temperature. At high fluences some metastable phases can be formed. To determine the surface modifications induced by ion implantation it is absolutely necessary to use various techniques very sensitive to rather low concentrations of impurities or able to probe very thin layers. An illustration of this necessity is given with studies of as‐implanted and annealed iron implanted sapphire and magnesium oxide surfaces. Rutherford backscattering spectroscopy (RBS‐c) was used to profile implanted iron and to follow lattice disorders as a function of annealing temperatures. Optical absorption spectroscopy and transmission electron microscopy have allowed the characterization of point defects and the determination of crystallographic structure of precipitates, respectively. The Mössbauer spectroscopy has allowed the determination of the charge states of implanted iron.
Topographic compensation in Auger electron spectroscopy
Authors: Sekine Tetsu , Sato Tomoshige , Nagasawa Yuji , Sakai Yuji
Published: May 2005

The scanning Auger microprobe (SAM) produces Auger images which provide information on the elemental distribution of specimen surfaces. However specimen topography affects the data obtained. To eliminate the topographical effect, the peak‐to‐background ratio, (P − B)/B ( = R), is often used instead of the net peak intensity, P − B. It was found that this method would provide reasonable quantitative results when the tilting angle of the facet plane against the primary electron beam incidence is less than approximately 50°. Over 50°, R would generally give higher values. At 80° R would be 1.2–3.7 times larger than that at 0°. In this paper we propose a new method to compensate for this deviation. Through specimen tilting experiments using a flat surface, we found a deformation of total background shape at high tilting angles. It is interpreted by γ, a background intensity ratio at two energies (ex. 2000 eV and 3000 eV). It was found that γ obeys a simple equation of tilt angle θ,

. Then, θ can be derived from the values of the background intensity ratios. The following relationship was also found between R0 and R

where R0 and Rθ are peak‐to‐background ratios at 0 and θ degrees, respectively, and E is the Auger transition energy. Since θ can be derived, we can always connect the peak‐to‐background ratio at θ to that in the horizontal state. Thus, elimination of topographic effect would be possible.

We believe that this scheme would contribute to quantitative Auger imaging.
A technique for performing angle‐resolved electron energy loss spectroscopy: A study of polycrystalline tin
Authors: Hoflund Gar B. , Corallo Gregory R.
Published: May 2005

A method is presented for performing angle‐resolved electron energy loss spectroscopy (ARELS) using a doublepass cylindrical mirror analyzer (CMA) which contains an angle‐resolving movable aperture. Both the electron gun contained in the CMA and an off‐axis electron gun are used in these studies. The technique is illustrated by ARELS spectra taken from a cleaned polycrystalline tin surface because observing the behavior of the surface and bulk plasmon features provides a direct and simple way of assessing surface sensitivity. The spectra demonstrate that the incidence angle of the primary beam, the collection angle with respect to the sample normal and the primary beam energy all have a very large effect on surface senstivity.
The status of reference data, reference materials and reference procedures in surface analysis
Authors: Grant J. T. , Williams P. , Fine J. , Powell C. J.
Published: May 2005

A brief synopsis is given of recent developments and current needs for reference data, reference materials and reference procedures in surface analysis. This assessment is based largely on three presentations and related discussion at the Second Topical Conference on Quantitative Surface Analysis held at Monterey, California on 30–31 October, 1987. While a reasonable start has been made in recent years in providing needed data, materials, and procedures, many important needs remain.
Problems of quantitative Auger analysis of TiNx thin films: Peak overlapping and line shape changes
Authors: Pamler W.
Published: May 2005

Quantitative Auger analysis of TiNx is not trivial because the only N transition coincides with a Ti peak and the shape of all Ti lines changes by compound formation. It will be shown in this paper that the effect of the line shape changes on quantification can be reduced by a degraded energy resolution, for example by additional smoothing of the raw spectra. Then, the overlap problem can be addressed by subtraction of an additional sensitivity factor which is determined by a pure Ti spectrum. Auger spectra will be quantified by means of reference samples. This calibration yields a good correlation of Auger intensities with bulk compositions. Moreover, the applicability of usual high resolution spectra for quantification will be discussed.
Application of AES micro‐analysis to interface characterization in TiSi diffusion couples: 2—Influence of oxygen
Authors: Quenisset C. , Naslain R. , Demoncy P.
Published: May 2005

The diffusion of both silicon and oxygen in TiSi couples annealed at 600–700°C under low (pO2 = 10−4 Torr) or high (i.e. in air) oxygen pressures has been studied by AES depth profiling. The AES quantitative analysis of titanium and oxygen was based on the computation of the peak height to background ratios vs. concentration curves for the Ti‐L3M23M23; Ti‐Li3M23M45 and O‐KL2L3 peaks. The element analysis was correlated with the peak shape and EELS spectra.

The diffusion of oxygen from the free surface of the sample within the titanium film slows down and eventually stops the extension of the titanium silicide layer formed by diffusion of silicon from the wafer. The former results in the formation of titanium oxides (i.e. TiO, Ti2O3, or TiO2) and the latter in that of titanium silicides (mainly Ti5Si3, and TiSi2). For long enough diffusion times, the main silicide in the diffusion zone is TiSi2 and its growth rejects oxygen in the titanium‐rich part of the couple. Therefore, the TiSi2/Si interface is almost free of oxygen.
The oxidation of zirconium as observed by Auger electron spectroscopy: A comparison of experiment and density of state calculations
Authors: Jungblut B. , Sicking G. , Papachristos T.
Published: May 2005

Several investigators found by using standard AES equipment that the peak‐to‐peak heights of the Zr signals in the energy range between 80 eV and 170 eV vary in an unusual way after exposure of the sample to oxygen.1–7 Normally the decrease of the Auger signal intensity is more pronounced for the metal signals of lower energy in comparison to those of higher energy. In contrast, in the case of Zr, an oxygen exposure leads to a strongly weakened 144 eV peak, whereas the signals in the energy range between 80 eV and 125 eV remain relatively unaffected.

In order to study this phenomenon, a series of high resolution spectra on Zr and ZrOx specimens was taken. The corresponding data sets were processed by applying algorithms for background correction, smoothing, and deconvolution resulting in AES spectra, which are almost free from experimental broadening and loss process artifacts. As a result of this procedure, it becomes apparent that with increasing oxygen content an additional peak gradually appears 7 eV below the 144 eV Zr signal, whereas the signals between 80 eV and 125 eV show minor line shape effects. This new marked Auger transition can be explained by the formation of an oxygen 2p band which enables cross transitions and interatomic transitions to take place. This is confirmed by the density of state calculation performed for tetragonal ZrO2,8 which reveals a O 2p band in the energy range from −4 eV to −8 eV below the Fermi level. Differentiated spectra of lower resolution, such as used for routine analysis, do not resolve these two signals and therefore show a broad peak of comparatively low intensity at 144 eV.
Characteristics of a conversion coating on aluminium
Authors: Crompton J. S. , Andrews P. R. , McAlpine E.
Published: May 2005

A study has been made of the film formed on an AlMgSi alloy by a chromate/phosphate solution. Transmission electron microscopy has been conducted to provide high resolution structural and elemental information about the film. The results show that the chemical species present in the film are similar to those reported for other systems. Structural analyses showed that the film may be composed of both particulate and non‐particulate regions. Small particles based primarily on chromium have been observed throughout the film thickness. Large particles at discrete locations along the film–metal interface are based on complex mixtures of chromium and aluminium. Complementary, x‐ray photoelectron spectroscopy has been used in conjunction with ion‐beam etching to provide chemical analysis through the film thickness.
An x‐ray photoelectron spectroscopic study of some chromium–oxygen systems
Authors: Desimoni E. , Malitesta C. , Zambonin P. G. , Rivière J. C.
Published: May 2005

A series of pure and mixed chromium standards has been analysed by x‐ray photoelectron spectroscopy in order to obtain a sufficiently homogeneous and self‐consistent set of spectral parameters to be used in the resolution of complex spectra. Additional information was obtained about the stability of the various species under Ar ion bombardment. The results relevant to potassium chromate and dichromate, chromous acid, chromium (III) oxide, hydroxide and nitrate are described and compared critically with those in the published literature.