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An international interlaboratory comparison of the measurement capabilities of four National Metrology Institutes (NMIs) and one Designated Institute (DI) in the determination of the chemical composition of thin Fe-Ni alloy films was conducted via a key comparison (K-67) of the Surface Analysis Working Group of the Consultative Committee for Amount of Substance. This comparison was made using XPS (four laboratories) and AES (one laboratory) measurements. The uncertainty budget of the measured chemical composition of a thin alloy film was dominated by the uncertainty of the certified composition of a reference specimen which had been determined by inductively coupled plasma mass spectrometry using the isotope dilution method. Pilot study P-98 showed that the quantification using relative sensitivity factors (RSFs) of Fe and Ni derived from an alloy reference sample results in much more accurate result in comparison to an approach using RSFs derived from pure Fe and Ni films. The individual expanded uncertainties of the participants in the K-67 comparison were found to be between 2.88 and 3.40 atomic %. The uncertainty of the key comparison reference value (KCRV) calculated from individual standard deviations and a coverage factor (k) of 2 was 1.23 atomic %. Copyright © 2011 John Wiley & Sons, Ltd.

A series of welds were fabricated in high strength low alloy 65 steel. The first pass went the entire length of the plate and each subsequent pass was indented ~25 mm. This allowed the authors to determine the change in hardness on a pass-by-pass basis by mapping the hardness over each weld pass.

A comparison of quantitative surface analyses of FeNi alloy thin films by various methods has been proposed as a pilot study by the Surface Analysis Working Group of the Consultative Committee for Amount of Substance (CCQM). To test the suitability of FeNi for this purpose, alloy films with different compositions were grown on Si(100) wafers by ion-beam sputter deposition and the compositions were certified by an isotope dilution method using inductively coupled plasma-mass spectrometry. The alloy compositions measured with X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) using sensitivity factors determined from pure Fe and Ni metal films agreed with the certified mean values to better than 2%. The alloy compositions quantified by secondary ion mass spectrometry (SIMS) with a C60 ion source agreed to better than 4% with the certified compositions if one of the alloys was used to establish the relative sensitivity factors (RSFs). These results indicate that the quantification of the FeNi alloy is a good method for a CCQM pilot study because matrix effects and ion-sputtering effects are small for these analytical methods. Copyright © 2007 John Wiley & Sons, Ltd.

B-doped Si multiple delta-layers (MDL) were developed as certified reference materials (CRM) for secondary ion mass spectrometry (SIMS) depth profiling analysis. Two CRMs with different delta-layer spacing were grown by ion beam sputter deposition (IBSD). The nominal spacing of the MDL for shallow junction analysis is 10 nm and that for high energy SIMS is 50 nm. The total thickness of the film was certified by high resolution transmission electron microscopy (HR-TEM). The B-doped Si MDLs can be used to evaluate SIMS depth resolution and to calibrate the depth scale. A consistency check of the calibration of stylus profilometers for measurement of sputter depth is another possible application. The crater depths measured by a stylus profilometer showed a good linear relationship with the thickness measured from SIMS profiling using the calibrated film thickness for depth scale calibration. The sputtering rate of the amorphous Si thin film grown by sputter deposition was found to be the same as that of the crystalline Si substrate, which means that the sputtering rate measured with these CRMs can be applied to a real analysis of crystalline Si. Copyright © 2005 John Wiley & Sons, Ltd.

A series of laser and laser assisted metal inert gas (MIG) welds was produced from a common plate. Each weld was mechanically tested, and the welds showed broadly similar properties, except for the autogenous CO2 laser weld metal, which had poorer toughness. This was related to a harder weld metal microstructure. Toughness and hardness were related to the lath width of the ferrite, for the welds involved. The weld metal area/volume was used as an indicator of potential distortion. In this instance, the autogenous CO2 laser weld was superior to the CO2 laser assisted MIG weld which was better than the Nd:YAG laser assisted MIG weld. Each weld was examined using carbon extraction replicas in the TEM, and also using an SEM with an EDAX attachment. A number of inclusions and precipitates were observed, identified and sized. It was concluded that the particles observed were not detrimental in this specific case. A tentative relationship was established between parent plate inclusion size distribution and weld metal inclusion size distribution.

We investigated the deconvolution of SIMS depth profiles of arsenic multiple delta layers in silicon. Two samples with spacings of 50 and 5/10 nm between the arsenic-doped silicon delta layers of thickness 1.0 and 0.5 nm, respectively, were used for the study. Time-of-flight SIMS analysis with sputtering of 0.5 keV Cs + at 45° incident angle has been performed to obtain the SIMS depth profile. We observed five clearly separated peaks in the 50 nm spacing sample but eight poorly separated peaks in the 5/10 nm spacing sample. After deconvolution, however, we could obtain very thin and sharp clearly separated peaks in both samples. The separability of the overlapping peaks was much improved, especially in the region of 5 nm spacing. An improvement in depth resolution by a factor of ∼3 and a gain in maximum peak intensity by a factor of ∼4 were achieved. We could not find any significant loss or gain of peak intensity during the deconvolution procedure. The physical validity of the deconvolution method is supported by non-destructive medium-energy ion scattering spectroscopy analysis, which can measure the thickness of the arsenic-doped silicon delta layer in a silicon matrix quantitatively.

We grew high quality In-rich InGaN/GaN single quantum well (SQW) structures by metal-organic chemical vapor deposition using growth interruption and obtained a sharp photoluminescence peak in near-ultraviolet (UV) region. During In-rich InGaN well layer growth, only TMIn and ammonia were supplied, however, atomic interdiffusion as well as defect generation occurred to relieve large lattice mismatch over 10% between InN and GaN. From medium-energy ion scattering measurement and subsequent fitting of the spectrum, we could find that the InGaN well layer was In-rich and it has 60-70% indium content. We also found the compositional grading of indium at top and bottom InGaN/GaN interfaces. The Fourier series method was used to calculate the energy levels and envelope functions in In-rich InGaN/GaN SQW with compositional grading and we could quantitatively explain the near-UV emission observed from the SQW.

A study was carried out for the measurement of ultrathin SiO on (100) and (111) orientation silicon wafer in the thickness range 1.5-8 nm. XPS, medium-energy ion scattering spectrometry (MEIS), nuclear reaction analysis (NRA), RBS, elastic backscattering spectrometry (EBS), SIMS, ellipsometry, gazing-incidence x-ray reflectometry (GIXRR), neutron reflectometry and transmission electron microscopy (TEM) were used for the measurements. Water and carbonaceous contamination about 1 nm were observed by ellipsometry and adsorbed oxygen mainly from water at thickness of 0.5 nm were seen by MEIS, NRA, RBS and GIXRR. The different uncertainty of the techniques for the scaling constant were also discussed.

A series of welds have been fabricated in high strength low alloy steel (HSLA100) plate by gas metal arc welding at heat inputs of 1.0, 1.6 and 2.2 kJ mm-1. Slices from the welds were then polished and the macrostructure was observed. Hardness maps were then determined over the entire weld zone, including the heat affected zone and the base plate. Correlations were then made between the hardness maps and the macrostructure. A bead on plate weld was made using the same heat inputs and was used to determine the temperature regimes in the weld as well as thermal profiles of the weld region. Relationships showing good correlations were observed between the various microstructures, the macrostructure, the calculated thermal profiles, and the hardness values.

Hybrid welding, the combination of laser and arc welding, is being heavily investigated for potential applications in the fabrication of structural steel components. The hybrid process is an alternative to autogenous laser welding that requires good fit-up of the parts. With the hybrid process, the addition of filler metal alters the weld pass chemistry and fills any gaps that may occur. In some applications, the fit-up of parts is only part of the issue for laser welding. In some structural steel components, the chemistry of the base metal when autogenously laser welded can result in weldments (weld metal and heat-affected zone (HAZ)) that have high hardness values. This indirectly indicates that the weld metal is brittle and not suitable for certain applications. The hardness values of the weldment have been used as an acceptance criteria for certain industrial applications. The use of hybrid welding may address the hardness issue. The addition of filler metal through a gas metal arc (GMAW) based hybrid process decrease the cooling rate in the HAZ therefore improving mechanical properties. These improvements can often be detected by microhardness profiles. While traditional hardness profiles tabulate hardness in a few regions of the weld, hardness mapping better profiles the hardness trends in the weldment. This paper will present welding results for the hybrid structural welding of a structural carbon steel using a 4 kW Nd:YAG based hybrid laser system. The data will center on the thermal response of the steel to the welding process, on the hardness mapping of the weldments and how the heat input altered the hardness and the mechanical properties of the welds.

A unique weld has been fabricated in HSLA100 steel plate by gas metal arc welding at a heat input of 1.0 kJ mm-1. The initial pass was made over the entire length of the plate (~750 mm). Each subsequent pass was indented approximately 25 mm and then made over the remaining length of the plate. This configuration allowed the consequence of a subsequent weld pass on the prior weld beads to be examined by slicing the welds at appropriate positions along its length. These slices were then polished and the macrostructure was determined. Hardness maps were then determined over the entire weld zone, including the heat affected zone and the base plate. Correlations were then determined between the hardness maps and the macrostructure. A bead on plate weld was made at the same heat input and was used to determine the temperature regimes in the weld as well as the thermal profile from these areas. Relationships are established between the various microstructures, the macrostructure, the calculated thermal ...

The damage distributions in Si(1 0 0) surface after 1.0 and 0.5 keV Ar+ ion bombardment were studied using MEIS and Molecular dynamic (MD) simulation. The primary Ar+ ion beam direction was varied from surface normal to glancing angle. The MEIS results show that the damage thickness in 1.0 keV Ar ion bombardment is reduced from about 7.7 nm at surface normal incidence to 1.3 nm at the incident angle of 80°. However, the damage thickness in 0.5 keV Ar ion bombardment is reduced from 5.1 nm at surface normal incidence to 0.5 nm at the incident angle of 80°. The maximum atomic concentration of implanted Ar atoms after 1 keV ion bombardment is about 10.5 at% at the depth of 2.5 nm at surface normal incidence and about 2.0 at% at the depth of 1.2 nm at the incident angle of 80°. However, after 0.5 keV ion bombardments, it is 8.0 at% at the depth of 2.0 nm for surface normal incidence and the in-depth Ar distribution cannot be observable at the incident angle of 80°. MD simulation reproduced the damage distribution quantitatively.

Medium energy ion scattering spectroscopy (MEIS) could identify ∼1 nm interface layer with compressive strain, which depends sensitively on the interface treatment conditions such as oxynitridation, ozone oxidation, tilt of Si(0 0 1) substrates. The interface strain relaxation always shows improvements in gate oxide reliability. Atomic scale investigations of strain profiles with MEIS are reviewed for SiO 2 /Si(0 0 1) interfaces.

SIMS quantification and depth scale calibration has been based on ion implanted standards. In this work, the feasibility of using multiple delta layer reference materials for quantitative SIMS depth profiling is tested and presented. Preliminary studies on application of multiple As delta layer Si thin films to shallow junction analysis will be presented and discussed.

The in-depth concentration of Ar atoms in Si surface after Ar + ion sputtering was investigated using medium-energy ion spectroscopy (MEIS) and dynamic Monte Carlo simulation. The primary Ar + ion energy was 0.5, 1 and 3 keV, and the primary Ar + ion beam direction was varied from surface normal to glancing angle. In the case of the surface normal incidence, the MEIS result shows that the maximum atomic concentration of Ar atoms increases from 6% at the depth of 2 nm to 16% at the depth of 3 nm as the primary ion energy increases from 0.5 to 3 keV. However, in the case of the incident angle of 80°, that is 2.5% at the depth of 1.5 nm when the primary energy is 3 keV, in-depth Ar distribution cannot be observable when the primary ion energy is 0.5 keV. Dynamic Monte Carlo simulation reproduced the in-depth concentration distribution of Ar atoms quantitatively.

An experimental gas-metal arc (GMA) weldment of HSLA-100 steel fabricated with an ultralowcarbon (ULC) consumable of interest for United States Navy applications, designated “ARC100,” was studied to determine the relationships among the microstructure, the solute redistributions at various positions across the weldment, and the local properties (microhardness). These relationships were investigated by a variety of techniques, including microhardness mapping, optical microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) (including compositional X-ray mapping), and parallel electron energy-loss spectroscopy (PEELS). The microconstituents observed in this weld include lath ferrite, degenerate ferrite, lath martensite, retained austenite, and oxide inclusions; no carbides or other solid-state precipitates are present within the weld metal. Microhardness mapping indicates an undermatched weld metal (lower hardness as compared to the base plate) in which the hardest regions are in the first and last top beads, the root passes, and between highly ferritic soft bands associated with the outer portion of each weld bead’s heat-affected zone (HAZ) (within the fusion zone). The majority of the gradient in the substitutional alloying elements (Ni, Cu, Mn, and Cr) occurs within a region of less than about 0.5 mm of the fusion boundary, but the composition still changes even well into the fusion zone. Appreciable segregation of Ni and Cu to solidification cell boundaries occurs, and there is appreciable enrichment of C, Ni, Cu, and Mn in thin films of interlath retained austenite. This ULC weld metal is softer than the base plate due to the preponderance of lath ferrite rather than lath martensite, even at the high cooling rates experienced in this low-heat-input weld. Alternatively, the strength of the weld metal is due to the presence of at least some untempered lath martensite and the fact that the majority of the ferrite is lath ferrite and not polygonal ferrite. The interlath retained austenite might enhance toughness, but might also serve as a source of hydrogen in solution, which could potentially contribute to hydrogen-assisted cracking.

Application of the so called mixing-roughness-information (MRI) depth model to quantitative reconstruction of the in-depth distribution of the composition is demonstrated by comparing secondary ion mass spectroscopy (SIMS) and Auger electron spectroscopy (AES) depth profiles. A GaAs/AlAs reference sample consisting of two layers of AlAs [1 and 36 monolayer (ML)] separated by 44 ML of a GaAs matrix was depth profiled using almost identical sputtering conditions: Ar+ ions of 3 keV impact energy and 52° (SIMS: CAMECA 4f ) and 58° (AES: VG Microlab 310F) incidence angle. Both the Al+ intensity of the SIMS profile and the Al (LVV) intensity of the AES profile were quantified by fitting the measured profiles with those calculated with the MRI model, resulting in the same mixing length of 3.0±0.3 nm, similar roughness parameter (1.4–2 nm), and negligible information depth (0.4 nm). Whereas practically no matrix effect was observed for AES as well as for Al+ in the SIMS profile, quantification using dimer (Al2+) ...

Samples of Si(100) single crystals have been implanted with As+ ions of 1.00 MeV to a dose of ∼5 × 1014 cm−2 at room temperature. Transmission electron microscopy and combined Rutherford backscattering spectrometry and channelling experiments with a 2.10 MeV He+ beam have been performed on the implanted samples to study the lattice location of As atoms and resultant defect configuration after implantation and annealing at 850°C for 30 min. Single alignment angular distributions along [100] and [110] axes and a (110) plane for He+ scattering from both the As and Si atoms at the same depth were measured and presented. The experiments were compared with simulated scans, calculated with the use of a Monte Carlo method, for a variety of assumed lattice sites. Although an inspection of channelling profiles indicates that practically all the As are on substitutional positions, these need not be true substitutional positions as it includes defect complexes. Analysis of the data for As, by comparing with ...

Due to the complicated artefacts in SIMS depth profiling, SIMS depth resolution is difficult to evaluate. For evaluation of the SIMS depth resolution, delta-doped layers are more useful than sharp interfaces, because the matrix effect and the sputtering rate change can be minimized in profiling through delta layers. The GaAs delta-doped layers in Si were grown and proposed as a reference material for the evaluation of SIMS depth resolution. The SIMS depth resolution was estimated using the analytical expression based on a double exponential with a Gaussian, and its dependence on SIMS analysis conditions such as ion energy, ion species and incidence angle was studied with the proposed GaAs delta-doped multilayers in Si. Copyright © 2000 John Wiley & Sons, Ltd.

S.-J. Kahng,1 Y. H. Ha,2 J.-Y. Park,1 S. Kim,2 D. W. Moon,3 and Y. Kuk1,* 1Center for Science in Nanometer Scale and Department of Physics, Seoul National University, Seoul, 151-742, Korea 2Department of Chemistry, Korea Advanced Institute of Science and Technology, Taejon, 305-701, Korea 3Surface Analysis Group, Korea Research Institute of Standards and Science, Taejon, 305-606, Korea (Received 27 February 1998)

The problem of the surface damage due to ion bombardment has remained to be understood and solved. Especially for surface analysis tools such as XPS or AES sputter depth profiling, and SIMS, where sputtering processes are used, the detailed understanding of the surface damage process and the development of methods minimizing the surface damage are very important to get the original informations of the analyzed specimens. In this work, the effect of the incident angle on the formation of the altered surface layer of Ta2O5 thin film and the surface amorphization process of Si(100) surface due to Ar+ ion bombardment was studied with Medium Energy Ion Scattering Spectroscopy and Computer Simulations by Molecular Dynamics and Monte Carlo methods. Emphases were given on the extreme glancing incident angle of 80°, because it significantly minimized the radiation damage of Si and the preferential sputtering for Ta2O5.

Interfacial reactions as a function of the stack structure of Al2O3 and HfO2 grown on Si by atomic-layer deposition were examined by various physical and electrical measurements. In the case of an Al2O3 film with a buffer layer of HfO2, reactions between the Al2O3 and Si layers were suppressed, while a HfO2 film with an Al2O3 buffer layer on the Si readily interacted with Si, forming a Hf–Al–Si–O compound. The thickness of the interfacial layer increased dramatically after an annealing treatment in which a buffer layer of Al2O3 was used, while no change in thickness was observed in the film in which a HfO2 buffer layer was used. Moreover, the stoichiometric change caused by a different reaction process altered the chemical state of the films, which affected charge trapping and the interfacial trap density.

Ultrathin SiO2 grown by plasma-assisted oxidation (plasma oxide) has been investigated by high-resolution x-ray photoemission spectroscopy and medium energy ion scattering spectroscopy. We found that the plasma oxide grown at the low temperature of 400°C has a thinner transition layer than conventional thermal oxide. This thinner transition layer in the plasma oxide not only decreased the gate leakage current effectively, but also enhanced the reliability of the gate oxide. We attribute these electrical properties of the plasma oxide to the reduction of the transition layer.

The characteristics of N-incorporated HfO2–Al2O3 alloy films (HfAlO) were investigated by high-resolution x-ray photoelectron spectroscopy (XPS), near-edge x-ray absorption fine structure (NEXAFS), medium-energy ion scattering (MEIS), and capacitance–voltage measurements. The core-level energy states, Hf4f and Al2p peaks of a 15A thick film showed a shift to lower binding energy, resulting from the incorporation of nitrogen into the films. Absorption spectra of the OK edge of HfAlO were affected mainly by the Al2O3 in the film, and not by HfO2 after nitridation by NH3 annealing. The NEXAFS of NK edge and XPS data related to the chemical state suggested that the incorporated N atom is dominantly bonded to Al2O3, and not to HfO2. Moreover, MEIS results implied that there is a significant incorporation of N at the interface between the alloy film and Si. The incorporation of N effectively suppressed the leakage current without an increase in interfacial layer thickness, while the interfacial state of the N-i...

The interfacial characteristics of gate stack structure of HfO2 dielectrics on strained Si0.7Ge0.3 deposited by atomic-layer deposition were investigated. An interfacial layer including GeOx layers was grown on a SiGe substrate, and the thickness of the GeOx layer at the interfacial layer was decreased after the annealing treatment, while SiO2 layer was increased. The ∼50-A-thick HfO2 film with an amorphous structure was converted into a polycrystalline structure after rapid annealing at temperature of over 700 °C for 5 min. The interfacial silicate layer was effectively suppressed by GeOx formation, while the silicate layer was formed after the annealing treatment. GeOx formation in an as-grown film resulted in a decrease in the accumulation capacitance and an increase in the oxide trap charge.

The thermal stability of Gd2O3 films, containing added Zr, was investigated using various techniques. The structural characteristics of epitaxial Gd2O3 are maintained on the Si(111) substrate when the Zr is codeposited along with Gd. The incorporation of ZrO2 into Gd2O3 improves the crystallinity of the film and no interfacial layers were observed. In particular, the structural stability with no deformation is greatly enhanced, and silicate formation is drastically suppressed, up to an annealing temperature of 800 °C. The interfacial defects caused by extensive interactions between Gd and Si are also minimized.

Al2O3 incorporated HfO2 films grown by atomic layer deposition were investigated using various measurement tools. The accumulation capacitance of the Al2O3 incorporated into HfO2 film increases as the postannealing temperature increases because of changes in interfacial and upper layer thickness and in interfacial stoichiometry. The core-level energy state of a 15 A thick film shows a shift to higher binding energy, as the result of silicate formation and Al2O3 incorporation. The incorporation of Al2O3 into the HfO2 film has no effect on silicate formation at the interface between the film and Si, while the ionic bonding characteristics and hybridization effects are enhanced compared to a pure HfO2 film. Any dissociated Al2O3 on the film surface is completely removed by a vacuum annealing treatment over 850 °C, while HfO2 contributes to Hf silicide formation on the surface of the film.

The thermal stability of the HfO2–Al2O3 laminate gate stack grown by atomic layer chemical vapor deposition was investigated using medium-energy ion scattering spectroscopy and high-resolution x-ray photoelectron spectroscopy. The laminate structure was maintained up to 800 °C under ultrahigh vacuum conditions, while it was drastically degraded at 850 °C, resulting in silicide formation on the film surface. Dissociated oxygen in the Hf–Al-oxide preferentially diffuses out through the film and desorbing at the surface. Volatile SiO species and Al–O components desorb through the sample surface, while HfO2 contributes to Hf silicide formation on the film surface.

Because the chemical states of the elements in SrTiO3 thin film on Si are reduced by argon ion beam bombardment, it was impossible to sputter depth profile the chemical states of SrTiO3 thin film by argon ion beams. In this paper, it is reported that the undistorted chemical states of Ti and Si at the SrTiO3/Si interface can be determined with oxygen ion beams at the appropriate 70° angle of incidence, with which either metallic Ti is not oxidized or Ti in SrTiO3 is not reduced. Under the sputter depth profiling conditions, the chemical state of Ti at the SrTiO3/Si interface could be successfully characterized and the effects of post-annealing at high temperature on the chemical state of Ti were studied. A significant number of Ti atoms in the metallic state were observed at the SrTiO3/Si interface without any post-annealing but all of them were oxidized to the Ti4+ chemical state after 2 h post-annealing at the temperatures above 600°C under oxygen flow. The dielectric properties of SrTiO3 thin films on Si were well correlated to the oxidation state of Ti and the broadening of the interface SiO2 layer induced by post-annealing at high temperature.

Sympathetic nucleation is defined as the nucleation of a precipitate crystal at an interphase boundary of a crystal of the same phase when these crystals differ in composition from their matrix phase throughout the transformation process. Following a brief history of the discovery and interpretation of this phenomenon, the means of identifying the presence of sympathetic nucleation are described. The morphological configurations most frequently produced by sympathetic nucleation are illustrated. Heterogeneous nucleation theory is then applied to explain sympathetic nucleation. Particular emphasis is placed upon the driving force for sympathetic nucleation, since many of the effects of phase diagram geometry and supersaturation upon sympathetic nucleation can be simply explained upon this basis.

Using secondary ion mass spectrometry (SIMS), ion scattering spectroscopy (ISS), direct recoil (DR) and X-ray photoelectron spectroscopy (XPS), we have studied the mechanism of oxygen enhancement of secondary ion emission. The secondary ion intensities were measured as a function of oxygen exposure for Fe and Co samples under static- and dynamic-SIMS conditions. In the static-SIMS, the intensity of Fe+ increased up to 60 L oxygen exposure and then slowly saturated. However, the intensity of Co+ had an additional peak at low oxygen coverage when compared with the result of Fe+. It sharply increased up to 5 L, dropping off around 20 L and increased again to saturation. Also the intensities of Fe+ and Co+ under dynamic-SIMS conditions showed similar changes to those under static-SIMS conditions. According to XPS spectra, the polycrystalline Fe surface was oxidized immediately on oxygen exposure. However the oxygen on the Co surface was changed from the chemisorbed state at low oxygen doses (0–5 L) to the oxide state at oxygen doses above 5 L. The relative oxygen coverages on Fe and Co samples estimated by DR and ISS intensities showed trends similar to the secondary ion intensities of Fe+ and Co+ as a function of oxygen dose. We applied the bond breaking model and the electron tunneling model for interpretation of the oxygen enhancement effect in the positive secondary ion emission for Fe and Co.

Direct measurements of strain depth profiles in Ge layers consisting of either pyramidal or dome-shaped nanostructures grown on Si(001) by gas-source molecular-beam epitaxy were obtained using medium-energy ion scattering spectroscopy. Layers consisting solely of pyramidal Ge structures (corresponding to total Ge coverages θGe=5.5 ML) exhibit a compressive strain of 2.1% which is uniform with depth. In contrast, Ge layers with a dome-shaped surface morphology (θGe=8.9 ML) undergo significant relaxation giving rise to a strain gradient which varies from 0.6% at the surface to 2.1% at the Ge/Si(001) interface.

High-quality epitaxial Pt films were grown by a sputtering deposition method using epitaxial Y2O3 as a dielectric buffer layer. A high degree of crystallinity was achieved with an ion-beam minimum channeling yield (χmin) of ∼11%, and a high degree of coherence between the film surface and interface was obtained for the Pt(111)/Y2O3(111)/Si, with a large lattice mismatch. High-resolution transmission electron microscopy results showed that the atomic arrangement at the interface between the Pt and the oxide was well ordered, and no perceptible interdiffusion was observed, even at an annealing temperature of up to 700 °C under an oxygen atmosphere. The atomic arrangement at the Pt/Y2O3 interface was drastically degraded after a high-temperature annealing at 900 °C due to the deformation of Y2O3.

The transient Si sputtering yield change of an amorphous Si for normal incident 500 eV O2+ ion bombardment under oxygen flooding condition was measured quantitatively with in situ MEIS. The Si sputtering yield decreased very rapidly from 1.4 Si atoms/O2+ at the initial stage to less than 0.1 Si atoms/O2+ at the steady state around 2×1016 O2+ cm−2. The change of the initial transient Si sputtering yield change corresponds to the 1.6 nm shift to the shallower depth in SIMS depth profiling.

A GaAs/AlAs superlattice growth by metal–organic chemical vapour deposition is being proposed as the single crystalline multilayer reference material for sputter depth profiling. This material was characterized by transmission electron microscopy experiments, which showed that the interface between GaAs and AlAs is atomically flat. The preliminary depth profiling experiments were carried out by AES and SIMS. The AES experiments were performed using a Perkin-Elmer SAM 660 scanning Auger microprobe and the SIMS experiments were carried out using a VSW multitechnique XPS/SIMS surface analysis system. The AES and SIMS sputter depth profiling experiments proved that the depth resolution was found to be almost constant for each interface when an Ar+ beam was used for sputtering. Therefore the sputtering-induced roughness is very small for this material with Ar+ beam profiling, the depth resolution deteriorated as a function of depth, indicating oxygen ion beam-induced surface roughening. For both AES and SIMS, the depth resolution improved for ion beams with lower kinetic energy and more glancing angles of incidence.

A method for the dry thermal oxidation of a strained SiGe layer is proposed. By oxidation of a graded Si1−xGex layer, the effect of Ge pileup was significantly reduced and the undesirable strain relaxation by defect formation is prohibited. After oxidation, the oxidized SiGe layer was homogenized by postannealing process, and thereby a SiO2/SiGe interface with good structural properties was obtained. During postannealing, the homogenization was significantly enhanced by strain-induced diffusion, and it was clearly proved by the uphill diffusion. This result can propose an alternative oxidation method of strained SiGe/Si heterostructures.

It is shown that point defects are predominantly generated by irradiating low energy noble gas ions onto a graphite (0001) surface. Scanning tunneling microscopic images of the graphite surface irradiated with 50 eV Ar+ ions show a structure corresponding to a point defect in which only one or two surface atoms are displaced. The process of ion penetration and trapping into the graphite is investigated as a function of ion energy in the range of 1–500 eV. Trapping efficiency rapidly increases with ion energy in the threshold region (10–100 eV), and leads to a saturation for higher energies. The penetration and trapping mechanism is discussed in relation to defect formation on the surface.

The strain state and the deformation profile of GaN quantum dots embedded in AlN have been measured by high resolution electron microscopy, medium energy ion scattering and grazing incidence X-ray diffraction. The results are compared with theoretical calculations, allowing one to conclude that GaN quantum dots experience a non biaxial strain which drastically decreases when going from the basal plane up to the apex of the dots. We also demonstrate that AlN is distorted in the surroundings of the dots, which provides the driving force for vertical correlation of GaN dots when the AlN spacer between successive planes is thin enough.

Medium energy ion scattering (MEIS) has been used to measure at the scale of the monolayer the deformation profile of self-organized GaN quantum dots grown on AlN by molecular-beam epitaxy. The effect of capping the GaN dots by a thin layer of AlN has also been studied. It is shown that GaN dots are partially relaxed in every situation. Capping them with AlN has little effect on the basal plane, as expected, but strongly modifies the strain of the upper part of dots. The experimental results are compared with theoretical calculations, allowing one to conclude that GaN quantum dots experience a nonbiaxial strain, which drastically decreases when going from the basal plane up to the apex of the dots.

We report on the absolute measurement of In coverage on the Si(111)4\ifmmode\times\else\texttimes\fi{}1-In surface using medium-energy ion scattering, and present bias-dependent scanning tunneling microscopy (STM) images. The In coverage was determined to be 1 monolayer (ML). This result is in contrast to previous results of 3/4-ML In determined by semidirect measurements using Auger electron spectroscopy and STM. Our result supports a 4\ifmmode\times\else\texttimes\fi{}1-In structural model consisting of four surface In rows, which was constructed from the recent surface x-ray diffraction study and tested by subsequent theoretical calculations. The bias-dependent STM images are well reproduced by ab initio simulations based on this 1-ML-In model.

Magnetic anisotropy evolution of ultrathin Co films grown on a Pt( 111) single-crystal surface is investigated by a UHV in situ surface magneto-optical Kerr effect (SMOKE) measurement. Perpendicular magnetic anisotropy inultrathin Co films is found to be persistent up to a thickness of 12 ML where the easy magnetization axis changes its orientation to an in-plane direction. The interface structure of an ultrathin Co overlayer on Pt(111) was investigated with atomic-layer resolution medium-energy ion scattering spectroscopy. For 7-ML Co, interdiffusion begins at 673 K to form a heavily distorted Co-Pt surface alloy layer with little change in SMOKE intensity. However, annealing at 773 K formed a 30-atomic-layers thick Co-Pt substitutional alloy with tensile strain, at which the SMOKE intensity increased by more than 200%. The enhancement of the Kerr intensity is discussed with the interface alloy formation.

The $\mathrm{Ba}/\mathrm{Si}(111)$ surface, previously known as a $3\ifmmode\times\else\texttimes\fi{}1$ phase, is found to have a $3\ifmmode\times\else\texttimes\fi{}2$ periodicity and a semiconducting band gap. The substrate reconstructs into the honeycomb chain-channel (HCC) structure with Ba atoms in the channel, as in the alkali-metal-induced $\mathrm{Si}(111)\ensuremath{-}(3\ifmmode\times\else\texttimes\fi{}1)$. However, the metal coverage is determined to be 1/6 monolayers, half the alkali-metal coverage. We propose that the structure and the metal coverage determined for the Ba adsorbate is universal for other alkaline-earth-metal adsorbates. With the alkali-metal-induced $3\ifmmode\times\else\texttimes\fi{}1$ case, our results lead to a rule that one donated electron per $3\ifmmode\times\else\texttimes\fi{}1$ surface unit is necessary to stabilize the HCC reconstruction of Si.

The Ba/Si(111) surface, previously known as a 3 x 1 phase, is found to have a 3 x 2 periodicity and a semiconducting band gap. The substrate reconstructs into the honeycomb chain-channel (HCC) structure with Ba atoms in the channel, as in the alkali-metal-induced Si(111)-(3 x 1). However, the metal coverage is determined to be 1/6 monolayers, half the alkali-metal coverage. We propose that the structure and the metal coverage determined for the Ba adsorbate is universal for other alkaline-earth-metal adsorbates. With the alkali-metal-induced 3 x 1 case, our results lead to a rule that one donated electron per 3 x 1 surface unit is necessary to stabilize the HCC reconstruction of Si.

We have investigated the electrical characteristics, junction depth and defect of ultrashallow junctions formed by using a plasma doping procedure. Compared with ultralow energy boron ion implantation at 500eV, the plasma doping process exhibits both a shallow junction depth and a low sheet resistance. The junction depths of the plasma doped samples were 15 nm and 33 nm after annealing for 10s at 900 °C and 950 °C, respectively. For the same junction depth, the sheet resistance of the B2H6 plasma doped sample is an order of magnitude less than that of the 500eV B ion implanted sample. Based on cross-sectional transmission electron microscope (TEM) and deep level transient spectroscopy (DLTS) analysis, the defects formed by the B2H6 plasma doping process can be completely removed by annealing at 950 °C for 10s.

The oxidation of Si(111) and Si(100) surfaces with the high-purity ozone(more than 98 mole %) was investigated with X-ray photoelectron spectroscopy (XPS). Thin oxide less than 3nm thickens was formed in an experimental chamber and the results showed that ozone oxidizes the (111) surface faster than (100) surface. Ozone does not show the temperature dependence on oxidation within the temperature range of 250–500 degree C for both (111) and (100) surfaces. Ozone proceeds the oxide formation at 700 degree C where oxygen does not proceed oxide formation rapidly.

This International Standard specifies procedures for estimating three depth resolution parameters, via the leading-edge decay length, the trailing-edge decay length and Gaussian broadening, in SIMS depth profiling using multiple delta-layer reference materials. This International Standard is not applicable to delta-layers where the chemical and physical state of the near-surface region, modified by the incident primary ions, is not in the steady state. Copyright © 2005 John Wiley & Sons, Ltd.

Amorphous La x Al y O films, containing 100, 50, and 30% La, were deposited by atomic layer deposition (ALD) on ultrathin SiO 2 films (1 nm). Changes in the depth profile, as a function of composition, and structure were examined by medium energy ion scattering and transmission electron microscopy. The electronic structure of the La x Al y O films was investigated by X-ray photoelectron spectroscopy as a function of La concentration and postdeposition annealing temperature. In the case of a pure La 2 0 3 film without Al 2 O 3 , the Si0 2 at the interfacial layer had been converted to SiO 2―x and La silicate during the ALD process. However, in case of a La 2 O 3 film with Al 2 O 3 , interfacial reactions were significantly suppressed. In particular, silicate formation in the La 2 O 3 films gradually increased with the increasing annealing temperature, while that in La 2 O 3 films incorporated Al 2 O 3 was suppressed up to an annealing temperature of 800°C.