半导体材料二次离子质谱定量分析中的基体效应

通过对Wilson等人由实验得出的Si，Ge，GaAs，GaP，InP，CdHgTe半导体和SiO2，Si3N4等绝缘基体中70多种注入元素相对灵敏度因子（RSF）值的综合分析，定义logFRS－Ii直线斜率为基体效应因子。发现基体效应因子值随基体平均原子序数的增加而增大，随基体平均电负性值的增大而减小，随基体氧化物生成热的增加而减小。应用本文提出的二次正离子发射理论分析式较好地解释了这些实验现象，并对影响基体效应的其他因素进行了进一步的讨论。     

Secondary ion mass spectrometry of dopant and impurity elements in wide bandgap semiconductors

Based on secondary ion mass spectrometry (SIMS) measurements, we have compiled state-of-the-art data concerning dopant elements and natural impurities in the wide bandgap semiconductor materials diamond, SiC, ZnSe, GaN and AlN. Samples were prepared by ion implantation of different elements into these materials and post-implantation thermal annealing. SIMS depth profiling techniques were used to determine atomic depth profiles of implanted elements and subsequent changes produced by annealing. Range statistics and SIMS relative sensitivity factors were established for major dopant and impurity elements in these wide bandgap materials. Results of these studies are presented in tabular form along with representative depth profile figures.     

Reduction of matrix effects in polystyrene/poly(methylene methacrylate) blends by metal-assisted secondary ion mass spectrometry

Secondary ion mass spectrometry (SIMS) is a very surface sensitive analysis technique with low detection limits. The main drawback of SIMS is its inherent incapability of providing quantitative information about sample compositions due to the frequent occurrence of ionization- and sputter-induced matrix effects. Metal-assisted SIMS (MetA-SIMS) is an experimental approach that consists in covering an organic sample with a minute amount of a noble metal prior to a static SIMS analysis, the main objective being an increase of the characteristic secondary ion intensities. We show in this article that MetA-SIMS is also a simple and efficient tool for reducing matrix effects in a set of polymer blend samples containing different relative concentrations polystyrene (PS) and poly(methylene methacrylate) (PMMA). These findings can be explained by diffusion processes leading to a sample surface configuration consisting of individual polymer chains embedded in a common Ag matrix.     

Simultaneous determination of the aerosol complex index of refraction and size distribution from scattering measurements of polarized light

In this study we attempt to determine the aerosol complex index of refraction and size distribution from scattering measurements of polarized light. We illustrate that the scattering matrix elements M(2)(100 degrees ) and D(21) (150 degrees ) can be selected as an optimum set of matrix elements for determination of the complex index of refraction. We also illustrate that errors increase if we include insensitive scattering matrix elements in the determination of the complex index of refraction. A method is developed for the simultaneous determination of the complex index of refraction and the size distribution. In our method, we selected two sets of matrix elements, M (2) (100 degrees ) and D (21) (150 degrees ), for the determination of the complex index of refraction and others, which are much less sensitive to the complex index of refraction than M(2) (100 degrees ) and D(21) (150 degrees ), for the determination of the size distribution, based on their sensitivity analyses. A modified inversion library algorithm is adopted to solve the coupled system. Numerical experiments show that both the complex index of refraction and the size distribution can be determined with reasonable accuracy when we apply our method to scattering measurements of polarized light.     

Problems Involved in Using Improper Calibration CRMs in Geochemical Analyses: A Case Study on Mafic Rocks of Boggulakonda Pluton, East of Cuddapah Basin, India

The performance and response of two commonly used certified reference materials (CRMs) for mafic rocks MRG-1 (CANMET, Canada) and JGb-1 (Geological Survey of Japan), both gabbroic in composition, are evaluated for a set of mafic plutonic rocks (gabbros) from Boggulakonda (BK) occurring to the east of Proterozoic Cuddapah Basin, South India. In this study, quadrupole-inductively coupled plasma mass spectrometry was used to generate trace and rare earth element (REE) data using MRG-1 and JGb-1 as calibration standards separately for a comparative study. It is found that the two CRMs show highly variable major, minor and trace element compositions except ΣREE. When used for BK gabbros, JGb-1 has yielded better results than MRG-1 with respect to trace elements (HFS elements Nb and Ta in specific), whereas a good agreement was observed between both CRMs for REE concentrations when compared with certified data. The Nb–Ta element distribution patterns for BK gabbros in the spidergrams plotted using JGb-1 as CRM show relatively prominent and pronounced negatively spiking anomalies with reference to Th, whereas using MRG-1 as calibration CRM yielded unresolved and unclear Nb–Ta anomalies in the present study. The geochemistry (major, minor and trace) of MRG-1 is different when compared to that of JGb-1. Probably this is reason for the disparity in the results obtained by inductively coupled plasma mass spectrometry on mafic plutonic rocks. The study conducted on the BK gabbros, reveals better and reliable results using JGb-1 as CRM. This study also reveals the importance of using proper CRM for calibration having closely matching trace and REE concentrations in addition to major and minor elements, for obtaining reliable data in geological samples.     

Matrices for immobilization of the rare earth–actinide waste fraction,synthesized by cold crucible induction melting

The structure of eight samples containing simulated rare earth–actinide fraction of high-level waste was studied. Samples of weight from 0.2 to 6 kg were prepared by cold crucible induction melting followed by crystallization of the melt. The target phases (britholite, pyrochlore, zirconolite, rhombic and monoclinic rare earth titanates) prevail in all the matrices; glass, zirconolite, and rutile were detected as impurities, sometimes in significant amounts. These phases do not contain waste components (rutile) or are stable in solutions (zirconolite); therefore, their presence should not impair the properties of the matrix. The possibility of controlling the phase composition of the matrix by introducing zirconium or aluminum oxide into the charge was demonstrated.     

Brannerite,UTi<Subscript>2</Subscript>O<Subscript>6</Subscript>: Crystal chemistry,synthesis, properties,and use for actinide waste immobilization

The host materials suggested for immobilization of actinide waste of military or civil origin often contain the secondary (U,Pu)Ti2O6 phase of brannerite structure. For example, the materials for incorporation of excess plutonium, mainly consisting of pyrochlore, contain up to 30% brannerite. This is a usual phase in titanate host materials for isolating spent nuclear fuel (SNF) and products of its reprocessing, including waste from production of ^99mТс for medical purposes and other kinds of waste with high U and Pu content. Despite simple ideal stoichiometry, brannerite can contain large amounts of rare earths. This feature is due to the presence of uranium not only in the 4+ oxidation state, but also in the 5+ and 6+ states, which favors the exchange of rare earth elements (REE), e.g., in accordance with the scheme 2U⁴⁺ ? U⁵⁺ + REE³⁺. The REE amount in brannerite reaches 0.5–0.7 atom per formula unit. Therefore, brannerite is of interest as a host material for the rare earth–actinide fraction of high-level waste (HLW). To evaluate the prospects for such use of brannerite, data on the radiation resistance of brannerite and its behavior in aqueous solutions are analyzed. In these properties, brannerite is inferior to pyrochlore and zirconolite. The rate of actinide leaching from brannerite is higher by an order of magnitude than from these phases, but lower by 3–4 orders of magnitude than from glass host materials. Natural brannerite is stable in media with weakly alkaline and reducing waters. Therefore, brannerite seems suitable for immobilization of rare earth–actinide waste. This host material can be synthesized by sintering or cold crucible induction melting followed by crystallization.     

Identification of cellular sections with imaging mass spectrometry following freeze fracture

Freeze-fracture techniques have been used to maintain chemical heterogeneity of frozen-hydrated mammalian cells for static TOF-SIMS imaging. The effects the fracture plane has on scanning electron microscopy and dynamic SIMS images of cells have been studied, but the implications this preparation method has on static SIMS have not been addressed to date. Interestingly, the chemical specificity and surface sensitivity of TOF-SIMS have allowed the identification of unique sections of rat pheochromocytoma cells exposed to the sample surface during freeze fracture. Using the extensive chemical information of the fractured surface, cellular sections have been determined using TOF-SIMS images of water, sodium, potassium, hydrocarbons, phosphocholine, and DiI, a fluorescent dye that remains in the outer leaflet of the cell membrane. Higher amounts of potassium have been imaged inside a cell versus the surrounding matrix in a cross-fractured cell. In other fractures exposing the cell membrane, phosphocholine and DiI have been imaged on the outer leaflet of the cell membrane, while phosphocholine alone has been imaged on the inner leaflet. In this paper, we discuss how imaging mass spectrometry isused to uniquely distinguish three possible sections of cells obtained during freeze fracture. The identification of these sections is important in choosing cells with a region of interest, like the cell membrane, exposed to the surface for a more thorough investigation with imaging static TOF-SIMS.     

Lithium isotope composition of basalt glass reference material

We present data on the lithium isotope compositions of glass reference materials from the United States Geological Survey (USGS) and the National Institute of Standards and Technology (NIST) determined by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS), thermal ionization mass spectrometry (TIMS), and secondary ionization mass spectrometry (SIMS). Our data on the USGS basaltic glass standards agree within 2 per thousand, independent of the sample matrix or Li concentration. For SIMS analysis, we propose use of the USGS glasses GSD-1G (delta(7)Li 31.14 +/- 0.8 per thousand, 2sigma) and BCR-2G (delta(7)Li 4.08 +/- 1.0 per thousand, 2sigma) as suitable standards that cover a wide range of Li isotope compositions. Lithium isotope measurements on the silica-rich NIST 600 glass series by MC-ICPMS and TIMS agree within 0.8 per thousand, but SIMS analyses show systematic isotopic differences. Our results suggest that SIMS Li isotope analyses have a significant matrix bias in high-silica materials. Our data are intended to serve as a reference for both microanalytical and bulk analytical techniques and to improve comparisons between Li isotope data produced by different methodologies.     

Quadrupole-based glow discharge mass spectrometer: Design and results compared to secondary ion mass spectrometry analyses

A design of quadrupole-based glow discharge mass spectrometer is briefly presented. A glow discharge occurs when a DC voltage (up to 3 kV) is applied between two electrodes in a cell filled with Ar at ∼1 hPa pressure. In this configuration, the sample acts as the cathode, and its surface (∼12 mm²) is sputtered by impacting Ar ions. The sputtered neutral atoms are ionised downstream in the plasma, and are extracted through a diaphragm to an energy filter and quadrupole spectrometer (6 mm rods) in high vacuum. The processes of sputtering and ionisation are separated, therefore reducing matrix effects.Preliminary results of elemental analysis of stainless steel, chromium-vanadium steel, Al-Mg-Cu and Armco alloys are presented. These results are compared to secondary ion mass spectrometry (SIMS) results obtained for the same set of samples using a 5 keV Ar⁺ ion beam and a quadrupole mass analyser (16 mm rods). The glow discharge mass spectrometry (GDMS) results allowed us to find SIMS relative sensitivity factors (RSF) for the analysed materials. Simple design and quick analysis time makes the new GDMS analyser an attractive tool in material technology.     

SIMS,EDX, EELS,AES, XPS study of interphases in nicalon fibre-LAS glass matrix composites

Secondary ion mass spectrometry (SIMS) and energy dispersive X-ray spectroscopy (EDX) were used to analyse interphases which develop at the fibre—matrix interface during fabrication of SiC nicalon fibre—LAS (Li₂O, Al₂O₃, SiO₂) or LAS+Nb₂O₅ glass matrix composites. SIMS was performed on fibres extracted from composites by dissolution of the matrix in hydrofluoric acid (HF). The composition of the interphases which remain on the fibre periphery was studied using sputter-depth profiling. EDX analysis of the interphases was performed on nicalon-LAS+Nb₂O₅ composite cross-sections. These investigations show that in both composites the reaction products at the fibre—matrix interface consist of a carbon layer and a silicate phase, rich in oxygen, located between the carbon layer and the fibre core. The analyses also demonstrate the efficiency of SIMS for analysing compositional changes in the near surface of fibres of small diameter.     

High-reactivity matrices increase the sensitivity of matrix enhanced secondary ion mass spectrometry

Secondary ion mass spectrometry (SIMS) is a desorption/ionization method in which ions are generated by the impact of a primary ion beam on a sample. Classic matrix assisted laser desorption and ionization (MALDI) matrices can be used to increase secondary ion yields and decrease fragmentation in a SIMS experiment, which is referred to as matrix enhanced SIMS (ME-SIMS). Contrary to MALDI, the choice of matrices for ME-SIMS is not constrained by their photon absorption characteristics. This implies that matrix compounds that exhibit an insufficient photon absorption coefficient have the potential of working well with ME-SIMS. Here, we evaluate a set of novel derivatives of the classical MALDI matrices α-cyano-4-hydroxycinnamic acid (CHCA) and 2,5-dihydroxybenzoic acid (DHB) for usability in ME-SIMS. This evaluation was carried out using peptide mixtures of different complexity and demonstrates significant improvements in signal intensity for several compounds with insufficient UV absorption at the standard MALDI laser wavelengths. Our study confirms that the gas-phase proton affinity of a matrix compound is a key physicochemical characteristic that determines its performance in a ME-SIMS experiment. As a result, these novel matrices improve the performance of matrix enhanced secondary ion mass spectrometry experiments on complex peptide mixtures.     

SIMS and RBS analysis of leached glass: Reliability of RSF method for SIMS quantification

The reliability of the relative sensitivity factor (RSF) approach for secondary ion mass spectrometry (SIMS) quantification of the leached layers on glass was investigated by measuring comparable samples of glass with SIMS and RBS (Rutherford backscattering spectrometry). The RSF factors were calculated using the nominal bulk compositions. Accurate results can be obtained only when the leached layer and the bulk glass have the same major elemental compositions (Si and O) and the matrix effect is inhibited. The concentrations of the different elements in the leached layer obtained from the comparable samples measured by SIMS and RBS are coincident within a factor of 2This paper is a part of a thesis submitted in partial fulfilment of the requirements for the PhD degree at the University of Technology of Vienna, 1991. The paper was orally presented in a symposium, Analysis of Working Materials, held in Vienna, 22–29 May 1991.     

Optimization of optical limiting devices based on excited-state absorption

Limiting devices protect sensitive optical elements from laser-induced damage (LID). Passive devices use focusing optics to concentrate the light through a nonlinear optical (NLO) element (or elements) to reduce the limiting threshold. Unfortunately, these NLO elements may themselves undergo LID for high inputs, restricting the useful dynamic range (DR). Recently, efforts at optimizing this DR have focused on distributing the NLO material along the propagation path z of a focused beam, resulting in different portions of the device (in z) exhibiting NLO response at different inputs. For example, nonlinear absorbers closer to the lens, i.e., upstream, protect device elements downstream near the focal plane. This results in an undesirable increase in the threshold, although the lowest threshold is always obtained with the final element at focus. Thus there is a compromise between DR and threshold. This compromise is determined by the material. We concentrate on reverse saturable absorber (RSA) materials (molecules exhibiting larger excited-state than ground-state absorption). We look at both tandem devices and devices in which the concentration of the NLO material is allowed to spatially vary in z. These latter devices require solid-state hosts. The damage threshold of currently available solid-state hosts is too low to allow known RSA materials to reach their maximum absorption, which occurs when all molecules are in their excited state. This is demonstrated by approximate analytical methods as well as by a full numerical solution of the nonlinear wave propagation equation over extremely large distances in z (up to 10(3)Z(0), where Z(0) is the Rayleigh range of the focused beam). The numerical calculations, based on a one-dimensional fast Fourier transform, indicate that proper inclusion of diffraction reduces the effectiveness of reverse saturable absorption for limiting, sometimes by more than a factor of 10. Liquid-based devices have higher damage thresholds (damage occurs to the cuvette wall) and, thus, larger nonlinear absorption. However, RSA material in liquid hosts may suffer from larger thermal lensing.     

SIMS studies of low-K materials

We report progress in conducting quantitative SIMS analyses of low-K materials. Electron-beam (e-beam) pre-irradiation of SIMS measurement sites was used to study the e-beam-induced effects on SIMS depth profiling of a porous organosilicate low-K material. Pre-irradiation of the sample surface using the e-beam causes a reduction in the thickness of the low-K film. SIMS profiling was used to sputter to identifiable marker positions within the pre-irradiated film. Physical measurement of the thickness of the remaining film was used to show that the e-beam-induced reduction in thickness occurs uniformly throughout the pre-irradiated film. Exposure of the film to the e-beam prior to SIMS analysis also resulted in minor changes in the composition of the film. However, pre-irradiation of the film is not part of the normal SIMS measurement procedure. We conclude that when the e-beam irradiation is used only for charge compensation during SIMS depth profiling, the SIMS analysis of the low-K material will not be significantly affected.     

Zyklische Beanspruchung drahtverstärkter Verbundstrangpressprofile mit Aluminiummatrix

Cyclic loading of wire‐reinforced aluminium matrix composite extrusions Aluminium matrix composite extrusions reinforced with wires featuring high strength and stiffness represent an innovative materials concept for lightweight structures. The use of reinforcing elements should improve the mechanical properties and hence enhance the performance of the lightweight structures. Composite extrusions made from the aluminium alloy EN AW‐6060 reinforced with reinforcing elements made from the spring steel 1.4310 and the cobalt‐base alloy Haynes 25 were examined under cyclic loadings which are of vital importance for the desired applications. Initially, load controlled multiple step tests at a load ration of R = ‐1 allowed for the determination of the cyclic stress‐strain‐curve. Afterwards, lifetime predictions were determined from these results by using mechanical models proposed by Morrow and Basquin, which were reviewed Woehler tests without mean stress. Furthermore, light and electron microscopy served for the clarification of damage and failure mechanisms. The investigations have been carried out with varying materials, configurations and surface treatments of the reinforcing elements. The investigations strived for the identification of the parameters’ influence on the lifetime behaviour to optimize the materials systems regarding the fatigue behaviour.     

Auger electron spectroscopy and secondary ion mass spectrometry depth profiling with sample rotation

Recently, there has been a rapid increase in the application of multilayered structured materials, as opposed to bulk materials, in many areas of technological development. Accurate characterization of the structure and composition of advanced multilayers such as superlattices, quantum wells, contacts, and coatings is important for materials and device fabrication technology. Surface analysis techniques including Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy, and secondary ion mass spectrometry (SIMS) in conjunction with ion beam sputtering (sputter depth profiling) are at present the most widely used methods for characterization of modern multilayer thin film materials and devices. Ion-beam-induced surface topography, however, can limit depth resolution, and with SIMS, can also cause changes in the secondary ion yield. These changes are due to the high sensitivity of secondary ion yield to the local angle of incidence on sputter-roughened surfaces. Degradation of depth resolution and changes in secondary ion yields during sputter depth profiling have often limited studies of thin film interdiffusion, segregation, oxidation at interfaces, and impurity effects. Much theoretical and experimental work has been carried out to try to improve depth resolution including the use of low ion beam energy, high angle of incidence, and two ion guns. Recent studies of AES and SIMS with sample rotation have shown that depth resolution can be improved substantially and that constant secondary ion yields in SIMS can be achieved. We will first provide an overview of the studies made by various groups to improve depth resolution of metal multilayers using AES with rotation. Next we will review recent investigations of SIMS using sample rotation including studies of the effects of sample rotation on O₂⁺ ion-beam-induced topography, secondary ion yield, and the depth resolution of electronic, metallurgical and dielectric materials. The results presented demonstrate that SIMS with sample rotation provides constant secondary ion yield, and depth-independent depth resolution because sample rotation prevents ion-beam-induced roughness and reduces the effect of the inhomogeneity of low energy ion beams.     

Transmission loss of phase-shifted fiber Bragg gratings in lossy materials: a theoretical and experimental investigation

Narrow linewidth transmission filters in lossy materials based phase-shifted fiber Bragg gratings have been investigated experimentally and analytically. A novel matrix technique has been developed in calculation of the transmission loss and linewidth. The elements of the matrix simply consist of the coefficients of the coupled mode equations. Simulation shows a small fiber loss could result in a significant transmission loss, which has not been explained properly yet to our knowledge. For phase-shifted gratings in erbium-doped fibers, the absorption could result in over 20 dB loss at transmission wavelengths. Such an approach can also be used to analyze cladding modes, radiation mode, and complex structure gratings.     

Changes in Polarization of a Light Beam with Arbitrary Autocoherence Propagating in a Birefringent Crystal

Based on the Mueller-Stokes matrix formalism and the Wolf autocorrelation functions, a general approach is developed for studying the polarization characteristics of a light beam with arbitrary autocoherence during its interaction with various media. This makes it possible to take into account the dispersion of the medium and the coherence properties of the light field. It is shown that the propagation of a polychromatic light beam with spectrally pure polarization in a certain medium can be described by an integrated Mueller matrix. For a linear phase plate, the matrix elements can be expressed by means of the modulus and the phase of the complex degree of autocoherence. The polarization of a light beam emitted by a black-body radiator and the influence of the dispersion in a KDP crystal in quasi-monochromatic light are discussed as applications.     

Local polarizability, structure, and charge-transfer in high-Tc superconductors

Using 2-band Peierls-Hubbard cluster and chain models, we illustrate the importance of polarizability and coupled charge-lattice-spin effects in complex electronic materials.We are grateful for discussions with many colleagues, particularly A. Bussmann-Holder, J. Mustre de Leon, H. Röder, Z. Tesanovic, and S. A. Trugman.