bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐spatial‐resolution surface imaging of inorganic and organic structures by multiphoton post‐ionization of sputtered neutrals and time‐of‐flight mass spectrometry
Authors: Tehorst M. , Möllers R. , Niehuis E. , Benninghoven A. 
Published: May 2005

AbstractNon‐resonant multiphoton ionization (NRMPI) of sputtered atoms as well as resonance‐enhanced multiphoton ionization (REMPI) of sputtered organic molecules in combination with time‐of‐flight mass spectrometry has turned out to be one of the most sensitive techniques for surface analysis. If, additionally, high spatial resolution is demanded the ionization process has to be extremely efficient since only a very limited amount of sample material is available. In preliminary investigations we used ultrashort and intense UV laser pulses (500 fs pulse width) for both elemental and molecular surface imaging. Images of an Ag‐coated Cu grid, an Au‐pattern on Si and surface structures of a biomolecule (tryptophan) and a polymer (polystyrene) are presented. Useful yields of up to 1% are achieved.
Sputtering effects in Si, SiO2 and the Si/SiO2 interface
Authors: Downey S. W. , Emerson A. B. 
Published: May 2005

AbstractResonance ionization mass spectrometry (RIMS) is used to determine the optimal sputtering conditions for sampling Si and SiO2 in depth profiling applications. Silicon RIMS signals are proportional to the Si concentration in these materials. Molecular formation during sputtering is significant with Xe+ at low energy (≤4 keV) and a high angle of incidence (∼60° from normal). Sputtering with Ar+ suppresses molecular formation. Because matrix effects are minimized with RIMS, pecularities in profiles at interfaces are easy to observe. The RIMS profiles of Ni and Co implants into SiO2 on Si show evidence of enhanced metal‐silicon bonding at the oxide/substrate interface.
The evolution of atomic scale topography by sputtering erosion
Authors: Carter G. , Nobes M. J. , Stoere H. , Katardjiev I. V. 
Published: May 2005

AbstractA numerical simulation of mediated random removal of atoms froma square array is presented. The removal probability is weighted according to the local surface orientation in order to model the effect of orientationdependent sputtering yield and it is demonstrated that this results in greatly reduced surface roughness development. This implies improved depth resolution in sputter lepth profiling over that predicted from equal probability random atomic removal processes.
FTIR Study on interfacial interactions between hydrated aluminium and polar groups in ethylene copolymers
Authors: Strålin A. , Hjertberg T. 
Published: May 2005

AbstractBy means of reflection‐absorption infrared spectroscopy, interfacial interactions were studied between hydrated aluminium and two ethylene copolymers, poly(ethylene‐c‐butyl acrylate) (EBA) and poly(ethylene‐c‐acrylic acid) (EAA). The hydrated aluminium surfaces were obtained by immersion in boiling water, which produces a pseudo‐boehmite film consisting of aluminium oxyhydroxide. This films of the polymers were prepared on the substrates by solution casting. Owing to the relatively large surface area of the substrates after hydration, it was possible to obtain spectra only representing polymer interacting with the surface. For EBA, the carbonyl absorbance of the bulk at 1735 cm−1 was displaced to 1698 cm−1 at the interface, owing to an interaction with the hydroxy groups on the hydrated surface. For EAA, on the other hand, a carboxylate was observed at the interface with the hydrated surface. The carboxylate formation and the large displacement of the carbonyl in the case of EBA indicate that strong bonds are formed at the interface. This is also supported by the results of the adhesive strength for EBA, where the locus of failure was changed from adhesive to cohesive.
XPS Study of the reduction of cerium dioxide
Authors: Romeo M. , Bak K. , El Fallah J. , Le Normand F. , Hilaire L. 
Published: May 2005

AbstractX‐ray photoelectron spectroscopy of cerium oxides is discussed. The well‐resolved 3d3/2 (5d 6s)0 4f0 2p6 peak at 916.70 eV cannot be used for calculating the amount of reduction because the correlation between its intensity and the concentration of Ce(IV) and CE(III) species is not liner. We have therefore develped a complete anlaysis of the whole spectrum. The deconvolution procedure is explained in detail and the method is applied to two examples: a CeO2/Al2O3 sample and a Pd/CeO2 catalyst reduced under hydrogen.
Characterization of the oxidation of tantalum nitride
Authors: Ibidunni A. O. , Masaitis R. L. , Opila R. L. , Davenport A. J. , Isaacs H. S. , Taylor J. A. 
Published: May 2005

AbstractSputter‐deposited non‐stoichiometric tantalum nitride films are used for laser‐trimmed thin‐film resistors owing to their stability and processability. The films are stabilized by heating in air to form a passive Ta2O5 film. This passive film can be destroyed if the resistors are exposed to aggressive thermal or chemical conditions. Thus we have studied sputtered TaN films and resistors deposited on SiO2 and Al2O3 substrates and exposed to either KOH solutions or air at 250–500 °C for various times. The oxidized films have been characterized with Auger electron spectroscopy (AES), x‐ray photelectron spectroscopy (XPS), x‐ray absorption near‐edge spectroscopy (XANES) and extended x‐ray absorption fine structure (EXAFS). Chemical shifts in the NOO Auger spectrum have been used to show that the initial fraction of deposited TaN reacts with the SiO2 surface to form Ta2O5. X‐ray photoelectron spectroscopy showed that although significant amounts of oxygen can be present in the sputered films, little of the tantalum is fully oxidized to Ta2O5. X‐ray photoelectron spectroscopy was also used to show that the oxide layer slowly increases in thickness when heated in air. Finally, KTaO3 was identified by XANES on the surface of films exposed to KOH. Once the passive Ta2O5 is converted to KTaO3, further oxidation of the underlying films occurs. The mechanism of oxidation of these films and the unique advantages of each spectroscopic technique are discussed.
A new experimental procedure for the backscattering correction in Auger analysis
Authors: Benhayoune H. , Jbara O. , Thomas X. , Mouze D. , Cazaux J. 
Published: May 2005

AbstractFrom the experimental determination of the electron backscattering factor η (using a positively polarized specimen holder) and applying an analytical expression correlating η and the Auger backscattering factor r, we demonstrate experimentally the possibility of correcting Auger spectra and profiles from the backscattering effects.
A calculation method for analysis of SIMS spectra from oxidation of metals in H216O/H218O/16O2 gas mixtures
Authors: Lu Q. , Hultquist G. , Tan K. L. , Åkermark T. 
Published: May 2005

AbstractA calculation method for the secondary ion mass spectrometry (SIMS) analysis of the reaction of a pure metal with gas mixtures of water and oxygen is introduced. Equation systems are to be solved, each expressed as: Y = A × X, where Y is an amplitude column measured from the SIMS spectrum, A is a matrix constructed from the relative abundances of isotopes of the metal and X is an unknown amplitude column of the relevant species MeaOHb±(a = 1, 2; b = 0, 1, 2 and 3). The applicability of the calculation method has been tested in SIMS analysis of ex situ‐grown iron oxides with different and known 18O contents. In in situ oxidation, measurement of the ratio of H216O/H218O in the metal–water–oxygen reaction allows fractions of O in the species MeaOHb+ that originate from water to be calculated. Data from such calculations have been used to study the initial stage of the reaction of Fe and Cr in H216O/H218O/16O2 gas mixtures. The results are interpreted in terms of coupled/uncoupled reaction type, reactivity of metal to water relative to oxygen in the mixed gas and degree of dissociation of water.
Photoelectron spectroscopic and surface resistance measurements of TiO2 and V2O5 after rare‐gas sputtering
Authors: Sasaki Teikichi A. , Baba Yuji , Yamamoto Hiroyuki , Sasase Masato , Isobe Shoji 
Published: May 2005

AbstractInsulating to semiconducting transformation was observed for surface layers of the transition metal oxides exposed to 1.5–15 keV He+, Ar+ and Xe+ ions. The surface electrical conductivity increased with the fluence of the ion beams and reached ∼10Ω−1 cm−1 at a fluence of 1 × 1017 Ar+ cm−2. Core‐line splittings in the metal 2p region and preferential losses of the surface oxygen observed in the x‐ray photoelectron spectra give evidence of the formation of the reduced chemical species Ti(II), Ti(III) and V(III). The ion bombardment also brought about the appearance of a new peak near the Fermi level in the UV photoelectron spectra. These observations suggest that electrons in the O 2p orbital are transferred to the 3d‐derived non‐bonding level by the losses of atomic oxygen and thus behave as charge carriers, which causes an increase in electrical conductivity.
Reconstruction of the depth profile from angle‐resolved AES/XPS
Authors: Dwyer V. M. 
Published: May 2005

AbstractThe effects of elastic scattering on the information available from angle‐resolved electron spectroscopies on noncrystalline materials is studied. These effects force the consideration of elastic scattering cross‐sections which are dependent on atomic concentration and therefore on depth. This is done by discretizing the transport equation within a two‐stream/transport approximation. The variation of inelastic mean free paths with composition is also included.It is also pointed out that, in addition to the ill‐conditioning problems and the possible numerical non‐uniqueness, the inversion of the Laplace transform required for reconstruction of the depth profile introduces a second analytical non‐uniqueness. It is suggested that the reconstruction of the depth profile should be performed using a highenergy peak to obtain an approximate depth profile (large inelastic mean free path, high depth penetration) and that the full quantification should be performed on a low‐energy peak (small inelastic mean free path, low depth penetration).
Structural and electrical study of 〈Au/InP(100)〉 and 〈Au/InSb/InP(100)〉 systems
Authors: Bideux L. , Gruzza B. , Porte A. , Robert H. 
Published: May 2005

AbstractThe mechanisms for the formation of the systems 〈Au/InP(100)〉 and 〈Au/InSb/InP(100)〉 are connected with their electrical properties. By using quantitative AES, a precise knowledge of the atomic mechanisms allows us to perform the desired component such as a Schottky diode. The best results are obtained for the 〈Au/heated InSb/InP〉 system with a barrier height of 0.7 eV.
Influence of metallurgy on the protective mechanism of chromium‐based conversion coatings on aluminum–copper alloys
Authors: Hagans Patrick L. , Haas Christina M. 
Published: May 2005

AbstractSeveral important aspects relating to the mechanism of formation of protective Cr‐based oxide films on aluminum alloy 2024‐T3 generated from CrO3 + NaF‐containing solutions were observed with electrochemical, AES and XPS measurements. Although the film deposition rate and surface composition were very much influenced by the presence of both Fe‐ and Cu‐containing intermetallic phases, a uniform composition and thickness was eventually reached with increased coating time. This behavior is believed to be responsible for obtaining corrosion‐resistant films on such heterogeneous surfaces. Surface Cr was consistently found to be in both the 3+ and 6+ oxidation states in an approximately 40:60 ration, respectively, if x‐ray beam reduction of Cr(VI) was accounted for. The enriched Cu layer found on the surface of polished 2024‐T3 was found to remain intact during CrO film formation. The presence of Cr(VI) provides a ‘self‐healing’ aspect to the film's protective mechanism by remaining available for reduction to Cr(III) during oxidative attack. Addition of potassium ferro‐ or ferricyanide to the bath resulted in a film which obtained Fe, C and N enriched at the surface on both the matrix and intermetallic regions. These constituents were found, however, to be enriched and distributed throughout the entire depth of the film on the high Cu‐bearing intermetallic regions, suggesting that the formation of a Cu–ferrocyanide complex is responsible for the benefit derived from these compounds.
Characterization of ni on si wafers: Comparison of surface analysis techniques
Authors: Calaway W. F. , Coon S. R. , Pellin M. J. , Gruen D. M. , Gordon M. , Diebold A. C. , Maillot P. , Banks J. C. , Knapp J. A. 
Published: May 2005

AbstractThe need for improved characterization of materials used in the fabrication of semiconductor devices has been driven by the semiconductor industry's desire to increase device densities on substrate. This need is reflected in the analytical surface science community by efforts to develop methods for detection of trace impurities on semiconductor substrates at extremely low levels. With improvements in standard techniques continually occurring, and with new methods of trace analysis always being developed, it is important to assess the relative abilities of the suite of surface analysis techniques available for materials characterization and to develop well‐characterized standard samples for these comparisons. This paper reports on a collaborative effort to review the capabilities of several approaches to trace surface analysis. As a test case, Ni contamination of Si wafers in the dose range 1014−1010 cm−2 has been chosen. The emphasis of this paper will be on the capabilities of SARISA (surface analysis by resonant ionization of sputtered atoms) as an example of laser post‐ionization secondary neutral mass spectrometry for the detection of contaminants in the near‐surface region. Results on analyses of the same standard samples by other techniques will also be presented. These techniques include total reflection x‐ray fluorescence and heavy ion backscattering spectrometry. The results of this comparison show that there are several techniques that can accurately determine metal contaminations on Si wafers in this concentration range and that the method of choice depends on other considerations, such as speed or accuracy of analysis.
Investigation of diamond films for electronic devices
Authors: Mearini G. T. , Krainsky I. L. , Dayton J. A. 
Published: May 2005

AbstractDirect dependence of secondary electron emission (SEE) from diamond films due to surface hydrogen has been observed. High secondary yields (14–27) have been achieved in polycrystalline diamond films on molybdenum substrates by varying the hydrogen content on the surface. This was accomplished by driving hydrogen from the bulk by heating the sample, or by adsorption of hydrogen onto the surface from direct hydrogen exposure. However, exposure to an electron beam depleted the surface of hydrogen as a function of current dosage in the energy range 300 eV‐3 keV, thereby reducing the secondary yield to a value as low as 3. Recovery of the secondary yield in the as‐deposited samples was facilitated by saturating the surface with hydrogen, as mentioned, and the recovery time has been characterized. The partial pressure of hydrogen could be adjusted so that the high secondary yield remained stable during beam exposure. The unique properties of these diamond films make them potentially useful as secondary emitters in electronic component designs. A special sample‐holder assembly has been constructed to test the feasibility of using these polycrystalline diamond films as dynodes in an electron amplifier. Actual gain at a hydrogen partial pressure of 1.0 × 10−T Torr was measured to be 2.4 × 104. The maximum gain expected was 2.4 × 105.
Hydrogen profiles in the surface of reduced lead‐silicate glasses
Authors: Rigato V. , Mea G. Della , Pantano Carlo G. 
Published: May 2005

AbstractIt is shown that the thermochemical reduction of alkali‐lead‐silicate glass does not lead to any significant incorporation of hydrogen in the surface, but greatly sensitizes the surface to the chemical and physical adsorption of water. The treatment creates a thin (25 nm) compositionally modified layer of silica‐rich, perhaps microporous, glass at the surface where the hydrogen concentration due to adsorption is irreversible. A more uniform, in‐depth hydrogen profile that extends thousands of angstroms into the treated surface is reversible. The time and temperature of thermochemical treatment influence the initial kinetics of the adsorption. These observations are of practical significance to the behavior of electron multiplier and microchannel plate devices that have been exposed to humid environments. It is demonstrated that vacuum annealing after heat treatment can be used to limit the rate and extent of water adsorption.
Emission of MCs+ secondary ions from semiconductors by caesium bombardment
Authors: Gnaser H. , Oechsner H. 
Published: May 2005

AbstractThe emission of MCs+ molecular ions sputtered from a variety of elemental (Si, Ge, a‐C:H) and compound (GaAs, InP, InSb, ZnTe, ZnMnTe, ZnSe, CdS, CdSe, CdTe) semiconductors by Cs+ ion impact was investigated. The energy spectra of MCs+ species were found to be very similar to that of Cs+ ions but, in most cases, are shifted slightly (∼1 eV) to higher energies. The useful yields of MCs+ secondary ions range from 10−6 (for HCs+) to 10−4 and, for a given molecular species, are largely independent of the specimen. For a series of Ge1‐xOx samples it was established that the GeCs+ intensity is constant up to an oxygen content of ∼10 at.% but the emission of GeOCs+ ions is prominent above this value and constitutes a competing ejection channel.
Surface analysis of oxidized aluminium. 1. Hydration of Al2O3 and decomposition of Al(OH)3 in a vacuum as studied by ESCA
Authors: Nylund Anders , Olefjord Ingemar 
Published: May 2005

AbstractPure polycrystalline Al (99.998%) was oxidized in dry oxygen and water. The surface products formed were analysed by ESCA. The thicknesses of the amorphous Al2O3 formed during oxidation for 1 h in dry oxygen at 25°C and 250°C are 14 and 20 Å, respectively. During exposure of the oxidized sample to water a surface layer of amorphous Al2O3 in hydrated and Al(OH)3 is formed by the reaction: Al2O3 + 3H2O⇄2Al(OH)3. The hydroxide is not stable in a vacuum. During analysis in the ESCA instrument, Al(OH)3 is decomposed to Al2O3 and H2O because the equilibrium pressure of H2O is higher than the partial pressure of water in the vacuum system. It is found that a 7 Å thick layer of Al2O3 is formed on the surface of Al(OH)3. The binding energies of the Al3+(2p) and O2−(1s) signals recorded from Al2O3 formed on Al at 22°C and at 250°C are 75.8 and 532.7 eV, respectively. The binding energies of these peaks are 0.6 eV lower for a sample preoxidized at 250°C and then exposed to a humid atmosphere and immediately analysed. It is suggested that the change of the binding energy is due to set up of a space charge during exposure to a humid atmosphere. After exposure for a long time to a humid atmosphere the charging decays and the binding energies approach their normal values.
Practical interest of multicomponent standards for quantitative AES
Authors: Perrot‐Simonetta M.‐Th. , Lorenzon C. , Biscondi M. 
Published: May 2005

AbstractIn this paper, it is first emphasized that the parameters of the classic expression of the Auger signal can be grouped into three terms that are independent of each other: the first relative to recording conditions, the second to an i‐element Auger transition and the last to sample chemistry. Consequently, it is shown that, using a relevant multicomponent standard set, it is possible to free quantitative AES of alloys from experimental conditions. The set of standards has to contain all the elements of the sample; each standard has to contain at least one element of the sample and one element common with another standard. By using the described method, a library of mulitcomponent standard spectra can be created, which can easily be used by other laboratories.
Deposition of cationic yttrium on heterogeneous surfaces
Authors: Davis S. J. , Watts J. F. , Hazell L. B. 
Published: May 2005

AbstractThe cathodic deposition of yttrium on iron and steel surfaces is known to improve the bond strength of joints treated in such a manner. This work explores the effect of large and small heterogeneities on the spatial distribution of the deposited species. Two systems are investigated: 98% iron with micrometre‐scale inclusions, and a micro‐hardness indentation on gold‐coated iron. In the former case yttrium is identified (by XPS and SAM) to have been deposited in two concentration regimes: close to the inclusion (the cathodic area) the concentration is higher than elsewhere, and also contains iron produced by back‐deposition. At the identation the iron substrate is exposed at the corners to provide the prerequisite anodic site, cathodic deposition of yttrium is then observed both within the identation and on the undamaged gold surface at a lower concentration. The provision of spatially resolved analytical information by SAM, time‐of‐flight SIMS and imaging XPS enables the interrelationship of microstructural features and extent of cathodic deposition to be readily appreciated.
Experimental influences on the results of concentration depth profiling by ARXPS
Authors: Ebel H. , Ebel M. F. , Fischer H. , Schoßmann B. , Svagera R. 
Published: May 2005

AbstractAngular resolved XPS (ARXPS) makes it possible to determine film thicknesses, attenuation lengths of photoelectrons and depth profiles of compositions. The usual algorithms for evaluating thin film results (rectangular depth profile of composition) do not account for influences of count‐rate statistics, finite solid angle of electron acceptance, elastic scattering of electrons and surface roughness on the results. Computer simulations of ARXPS performed on specimens with rectangular depth profiles provide a better understanding of deviations from expected depth responses of composition due to these influences. The dominant influence of surface roughness on the results is demonstrated by a comparison of ARXPS performed on SiO2‐films on monocrystalline and on polycrystalline Si‐wafers.
Interfacial reactions and silicide formation in Si/Ni/Si and Si/Cr/Si sandwich layers
Authors: Zalar A. , Hofmann S. , Pimentel F. , Panjan P. 
Published: May 2005

AbstractThe preparation of well‐characterized silicide thin films for microelectronics needs a control of interfacial reactions and diffusion processes during heat treatment of metal/semiconductor systems. Two sandwich structures of Si(33 nm)/Me(50 nm)/Si(33 nm), where Me = Ni or Cr, with a total thickness of each structure of 116 nm were sputter deposited onto smooth silicon‐(111) substrates. The reactions of both metals with amorphous silicon thin films were activated in a differential scanning calorimeter (DSC), at a heating rate of 40°C/min−1, between room temperature and different higher temperatures. Auguer electron spectroscopy depth profiles showed that the Si/Ni/Si sandwich structure reacted almost completely during heat treatment up to 320°C and formed reaction products with a composition close to Ni3Si2. Selected area diffraction patterns revealed that this is a mixture of Ni2Si and NiSi silicides. A much less pronounced reaction between Si and Cr was observed in the Si/Cr/Si sandwich structure, even with heating to 630°C, resulting in CrSi2 silicide and different Cr–Si solid solutions. The results of AES depth profiling studies of the thermally treated sandwich structures are discussed in terms of diffusion processes, movement of interfaces and formation of silicides. The additional information obtained with differential scanning calorimetry and transmission electron microscopy enables a detailed identification of reaction products formed in the early stage of the thermally treated Si/Me/Si structures.