SIMS Study Research Articles

Pyroxene as a recorder of cumulate formational processes in asteroids, Moon, Mars, Earth; reading the record with the ion microprobe

Igneous cumulate rocks provide an important record of planetary magmatism, but there are pitfalls in their interpretation. Cumulus minerals may react with the trapped melt and other cumulus phases during sub solidus reactions, thus losing a direct record of their igneous history. One of the best approaches for estimating the melt compositions parental to the cumulates is to analyze the cores of cumulus phases for elements with slow diffusion rates (e.g., REE in pyroxene) because these most reliably retain a record of the mineralmelt partitioning. We have conducted SIMS studies of pyroxenes from a variety of planetary cumulates, including lunar norites, martian orthopyroxenites, asteroidal orthopyroxenites (diogenites), asteroidal pyroxene-plagioclase cumulates (cumulate eucrites), and terrestrial orthopyroxenites and norites (Stillwater Complex, Montana). We emphasized the REE (La, Ce, Nd, Sm, Eu, Dy, Er, Yb) along with Sr, Y, and Zr in these investigations. Our studies yielded the several conclusions. (I) Lunar Mg-suite norites crystallized from highly evolved (KREEPy) melts that were emplaced into the lunar anorthositic crust. One viable model suggests remobilization of KREEP lithologies that formed late in the crystallization of the lunar magma ocean. (2) Orthopyroxenites from asteroid 4 Vesta (diogenites) likely formed as cumulates from melts derived from depleted mantle, which had previously experienced eucritic basalt removal. The calculated parental melts show a limited range of major element compositions but an exceedingly large range of trace element variation that is difficult to explain by any simple crystallization or melting models. (3) The diogenites of 4 Vesta are cumulates from melts derived from many depleted mantle reservoirs that either formed numerous orthopyroxene plutons, later mixed by impact brecciation, or commingled by magma mixing to form a limited number of differentiated plutons. We base this conclusion on a comparative investigation of a well-studied terrestrial orthopyroxenite sequence (Bronzitite zone of the Stillwater Complex). An important lesson to be learned from these studies in comparative planetology is that if simple petrogenetic models do not work for well-studied terrestrial occurrences there is little reason to believe that they will work for planetary environments where we have little geologic control on sampling.

SIMS study on redistribution of implanted impurities in InSb and InAs during post-implantation annealing

The concentration profiles of beryllium and magnesium implanted in InSb and InAs at an energy of 200 keV and a dose of 10 15 cm −2 of beryllium and a dose of 5 × 10 14cm −2 of magnesium were investigated by SIMS analysis, in samples as-implanted and annealed at 300°C–800°C for InAs or at 300°C–450°C for InSb. It is found that in InSb samples the magnesium profiles did not broaden up to 350°C, but beryllium profiles did not even change up to 450°C. In InAs modification of the beryllium profiles in comparison with InSb occurred at relatively low temperatures about 400°C and an increase of annealing temperature from 400°C to 700°C resulted in a severe distortion of the original profile. At temperatures above 700°C a gettering layer in the region near R p resulted from the agglomeration of radiation defects. This layer acted as a sink of diffused beryllium.

Study of deuterium metal interaction by ion implantation

Dynamic and non-equilibrium effects involving interaction between deuterium and radiation produced defects were studied during deuterium implantation of Cu and Ti. The technique of neutron yield measurement during deuterium implantation was employed and theoretical analysis was made to study the dynamics. SIMS, GIXRD and SEM studies on deuterium implanted samples were employed to study the evolution of implanted deuterium profiles, structure of deuterides and surface topography respectively.

Sims and Moke Studies of Fe/Gd Multilayers on Si

AbstractTwo Fe/Gd/Fe/Gd multilayers with different layer thicknesses were grown on Si (100) by magnetron sputtering. The as-deposited samples were vacuum-annealed at 100°C, 200°C, and 300°C. They were studied by grazing incidence x-ray diffraction (XRD), secondary ion mass spectroscopy (SIMS), vibrating sample magnetometer (VSM) and magneto-optical Kerr effect (MOKE). The deposition rates for Fe and for Gd are (1-2) and 4 Å s−1, respectively. The XRD and SIMS data show that interdiffusion occurs between Fe and Gd layers, and between Gd and Si layers. The thicker multilayers show strong in-plane uniaxial anisotropy.

SIMS study of the interaction of methanol with clean Cu(100)

The interaction of MeOD (= M) with the clean Cu(100) surface at ~125 K was examined by low-flux (static) SIMS. The molecular character of the adsorption process was evident in the structure of the major secondary ion progressions detected, namely CuMn+, MnD+, MnOD− and MnMeO− (n=0,1,…). Above ~0.6 L exposure, MeOD adsorption was found to be spontaneously re and dependent on the partial pressure of MeOD. At this same exposure a threshold for enhanced emission of OH− (relative to OD−) and the larger secondary ion clusters was reached. It is suggested that typical MeOD condensation on Cu(100) proceeds initially by dispersion of an isolated dimeric species, rather than by nucleative growth as polymeric clusters, and that the ~0.6 L exposure threshold marks the onset of lateral inter-site adsorbate interactions, which are apparently repulsive in character. For MeOD partial pressures in excess of 5 × 10−8 mbar, a preferential attenuation of the yields of all clusters containing Cu takes place, which is attributed to multilayer MeOD condensation.

SIMS studies of planetary cumulates; orthopyroxene from the Stillwater Complex, Montana

SIMS studies of planetary cumulates; orthopyroxene from the Stillwater Complex, Montana

A SIMS study of embedded primary atom (Ar + and Ne +) signals from Si and Ge surfaces under intense ion bombardment

SIMS signals of embedded primary atoms, +(Ar) and I +(Ne) generated from Si and Ge surfaces have been monitored as a function of bombarding energy ( E) as well as target current density ( J p). I +(Am) data supports the predominence of resonance charge transfer phenomenon above the target surface. Under Ne + bombardment, however, it is more likely that in addition to the charge transfer phenomenon, a significant fraction of secondary Ne + ions is produced in close binary encounters between NeSi and NeNe atoms within the solid by molecular orbital electron promotion - a phenomenon which is possible in the low keV region only for light ions. Our results might have some importance in the study of plasma confinement time in nuclear reactors where only light ions are used as initiating fuels.

Ion yield effects in the SIMS analysis of silicon delta‐doped layers in GaAs

AbstractEnhancements in the secondary ion yields of Si+ and As+ ions were observed in SIMS depth profiles of Si delta‐doped layers in GaAs when using oxygen primary ions. A systematic SIMS study of the enhancement in the intensity of the Si+ ion was carried out using a special test structure consisting of a series of layers with Si areal densities ranging from 0.01 monolayer (ML) to 2 ML (1 ML = 6.3 × 1014 Si cm−2). The enhancement effect was observed with layers above about 0.2 ML coverage and leads to erroneous measurements of the Si areal density for such layers. It was found that the level of the enhancement depended upon both the energy and angle of incidence of the oxygen ions. For a 2 ML delta, the level of the enhancement obtained with 5 keV O2+ ions at normal incidence was a factor of 1.2. However, using the same ion energy but changing the angle of incidence to 60° from the normal the enhancement obtained was almost a factor of 5. The enhancement was greatest when conditions for high depth resolution were used so that it was not possible simultaneously to achieve high depth resolution and accurate areal density measurements. The enhancements could not be removed by ratioing the silicon intensities to the As matrix lines (for which the enhancements are different). The enhancement effect was not observed when Xe+ or Cs+ primary ions were used and is predominantly an oxygen‐induced artefact.

SIMOX: processing, layer parameters design, and defects control

In this paper, some of the important results based on SIMS, RBS, ion channelling, and TEM studies of the as-implanted and annealed SIMOX materials are presented. The mechanisms responsible for the buried oxide layer formation are discussed, together with a semi-empirical model for the design of layer parameters and the concept of the dose window necessary for producing high quality SIMOX.

Pressure influence on the diamond deposition domain from various CHO(-Ar)-containing gaseous mixtures

Abstract Plasma volume can be increased through the addition of rare gas or by using low pressures. The influence of these deposition conditions on the diamond growth from CHO-(Ar)-containing gas mixtures was studied in a classical microwave plasma reactor. The morphology, grain size, growth rate and uniformity of diamond films were investigated by SEM and their quality was deduced by micro-Raman and SIMS studies. Their variations with different gaseous compositions and pressures are reported and discussed. It is especially shown that low pressures decrease the film quality and the diamond deposition domain. However, pressures in the range 2–5 Torr could be employed for mechanical applications, for example.

Cathodoluminescene at low Fe and Mn concentrations; a SIMS study of zones in natural calcites

ABSTRACT Point analyses of natural calcite cements by SIMS confirm the earlier suggestions that 20 ppm Mn is required to activate luminescence, whereas Fe concentrations in excess of 1400 ppm quench it partly, independently of the Mn content. Below this Fe threshold, luminescence is bright at Mn concentrations in excess of 225 ppm. In the range 20-225 Mn, all types of luminescence--dull, luminescent, and nonluminescent--can occur. This undifferentiated domain is evident also from a compilation of literature data. The type of luminescence is not a simple function of Fe and Mn concentrations; other parameters influence CL. Sinc most diagenetic calcite cements have Fe and Mn concentrations that place them within the field of mixed cathodoluminescence, these results force reassessment of models that equate the type of luminescence with the redox state of the diagenetic environment.

DIFFERENT INTERDIFFUSION CHARACTERISTICS BETWEEN Ag AND Al/YBa_2Cu_3O_(7-x) CONTACT INTERFACE

Different interdiffusion characteristics between the Ag/YBCO and Al/YBCO contact interfaces have been revealed by SIMS studies. The different electrical properties of Ag/YBCO and Al/YBCO interfaces after high temperature treatment are well understood by SIMS results.

Effective trap concentration in photo refractive CdTe: V and ZnCdTe: V crystals

From correlated SIMS and EPR studies on high resistive, vanadium doped CdTe and ZnCdTe bulk crystals we have determined the total V concentration [V] and the [V 3+] and [V 2+] concentration respectively. This allows us to estimate the effective trap concentration N eff=[V 2+][V 3+]/[V 2++[V 3+], which is one important parameter for photorefractive applications. The values of N eff obtained are in good agreement with those previously deduced from photorefractive measurements.

Formula omitted] multiple heterostructures on GaP substrates

In this paper we report on ZnGeP2GaP double and multiple heterostructures grown by organometallic chemical vapor deposition at 580°C, using dimethylzinc, trimethylgallium, germane and phosphine as source gases. With appropriate growth conditions, mirror smooth epitaxial ZnGeP2GaP multiple heterostructures are obtained on (001) GaP substrates. Cross-sectional SEM and TEM and SIMS studies show that the interfaces of these heterostructures are sharp and smooth. Etching studies of the top GaP (001) surface of GaP/ZnGeP2/GaP double heterostructures reveal a dislocation density of ∼ 5 × 104cm−2. Selected area 〈110〉 electron diffraction patterns show that the GaP layers crystallize in the zincblende structure and the ZnGeP2 layers crystallize in the chalcopyrite structure. This is the first time that multiple heterostructures combining these two crystal structures have been made.

SIMS study of rapid nitridation of silicon dioxide thick films in an ammonia ambient

Thick silicon dioxide films of 1.5 μm thickness have been nitrided at temperatures of 700°C and 800°C for 30, 60 and 300 s in a lamp-heated furnace at atmospheric pressure using ammonia. A mechanism of interstitial diffusion of ammonia, together with its reaction with silica, is suggested to explain the exponential shape of the nitrogen profiles in the nitrided 1.5 μm silica films. From this analysis we have extracted the values of the effective reaction coefficient k ★ and of the effective diffusion coefficient D ★ , both correlated by x o , the exchange length for the exchange of oxygen atoms by imine radicals.

SIMS study of rapid thermal nitridation of silicon dioxide thick films in ammonia ambient

Thick silicon dioxide layers (1.5 μm) have been nitrided in a lamp-heated furnace in an ammonia ambient. Temperatures of 700–1100°C were used for the nitridation for times of 5 to 300 s at atmospheric pressure. The distribution of the nitrogen in the nitrided samples was obtained using SIMS. The exponential shapes of the nitrogen profiles have been interpreted by a mechanism involving diffusion of the nitriding groups (NH 3) with a reaction with the network. We obtained the values of the effective diffusivity D ∗ = D NH 3 C 0 N i and of the reactivity k ∗ = k cn C 0 N i correlated by the length of exchange x 0 = ( D ∗ k ∗) 1 2 . It appears that the increase of k ∗ with the temperature is larger than the increase of D ∗. This finding implies a shorter length of exchange at high temperature than at low temperature.

XPS and static SIMS studies of copoly(ether–esters) containing mixed polyether soft blocks

AbstractThe surface compositions for a series of copoly(ether–esters) are determined from XPS and static SIMS measurements. The copolymers consist of a polybutylene terephthalate (PBT) hard block and a mixed soft block of two of the following polyethers—poly(propylene glycol) (PPG), poly(tetramethylene) oxide (PTMO) and poly(ethylene oxide) (PEO). The surfaces of all the copolymers are enriched in the total polyether soft blocks. Quantification of XPS intensities shows the presence of both polyethers at the surface of these mixed soft‐block copolymers, in relative amounts close to the bulk formulations. In the static SIMS measurements, direct observation of characteristic fragment ions related to the specific polyethers confirms their presence and relative abundance in the surface.

18O tracer study of the oxidation of zircaloy‐4 in steam

AbstractThe corrosion resistance of Zircaloy‐4, used as fuel cladding in pressurized water reactors, in steam at 400°C is related to the annealing temperature used in fabrication. This change in corrosion behaviour appears to be related to the size and composition of intermetallic compound precipitates, which vary with annealing temperature.A SIMS study has been undertaken to clarify the mechanisms responsible for these variations in the initial stages of corrosion of Zircaloy‐4. A set of samples subjected to different annealing temperatures have been oxidized, initially in normal steam and subsequently in steam enriched in H2 18O. Corrosion mechanisms have been followed using depth profiling in a Cameca IMS 3F microscope together with three‐dimensional depth profiles and imaging of taper sections using a gallium microprobe (VG Scientific).Iron and chromium, present in intermetallics in the alloy, remain localized within the oxide scale. The size and frequency of these local concentrations of iron and chromium reflect the distribution of these elements in the alloy. There is, however, some diffusion of these elements into the surrounding oxide, the iron diffusion being greater than that for chromium. The 18O tracer studies indicate that grain boundary transport of oxygen dominates the initial oxide growth process for Zircaloy‐4.

ToF SIMS study of the desorption of emulsifiers from polystyrene latexes

AbstractThe desorption of emulsifiers from the particle surface of polystyrene latexes prepared by emulsion polymerization has been studied by Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF SIMS). Two polystyrene latexes prepared with respectively sodium dodecyl sulphate and sodium dodecylbenzene sulphonate as emulsifiers were compared. It has been shown that the quasi‐molecular, parent ions and the characteristic fragments of the emulsifiers can easily be observed in positive and negative ToF SIMS. But these ions are more sensitive in the negative mode. The results have shown that after extensive purification with mixed‐bed ion‐exchange resins, the emulsifier was totally absent on the latex prepared with sodium dodecyl sulphate and that only traces of the emulsifier exist on the latex prepared with sodium dodecylbenzene sulphonate. These results suggest that strong acid emulsifiers can be desorbed by mixed‐bed ion‐exchange resins.

SIMS study of implantation-induced boron redistribution in silicon

Implantation damage was introduced into boron-doped p-type 〈111〉 silicon wafers of 0.013−0.02 Ω cm by 150 keV Ar + implantation at doses of 2 × 10 14 cm −2 (low dose) and 1 × 10 15 cm −2 (high dose), respectively. Thermal annealing was performed at 900°C and 1000°C in N 2 for various time intervals. Boron depth profiles in these samples were studied using SIMS. From the SIMS results, it is found that after annealing, significant boron redistribution has been induced in the high dose implanted samples, while such boron redistribution has not been observed in the low dose cases. The boron SIMS profiles of the high dose implanted and annealed samples are characterized by a peak and valley feature. The typical peak position is at a depth of around 0.05 to 0.1 μm and the typical valley position is at around 0.25 to 0.3 μm beneath the surface. Possible mechanisms of this implantation-induced boron redistribution in silicon are discussed.