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1.
Ion-induced secondary electron emission determined via sample current measurements (SCM) was employed as a useful adjunct to conventional secondary ion mass spectrometry (SIMS). This paper reports on the results of 3-6 keV O2+ SIMS-SCM sputter depth profiling through CrN/AlN multilayer coatings on nickel alloy, titanium dioxide films deposited on stainless steel, and corrosion layers formed onto surface of magnesium alloy after long-term interaction with an ionic liquid. For Au/AlNO/Ta films on silicon, in addition to SIMS-SCM profiles, the signal of mass-energy separated backscattered Ne+ ions was monitored as a function of the depth sputtered as well. The results presented here indicate that secondary electron yields are less affected by “matrix effect” than secondary ion yields, and at the same time, more sensitive to work function variations and surface charging effects. SCM depth profiling, with suppression of “the crater effect” by electronic gating of the registration system is capable of monitoring interfaces in the multilayer structure, particularly, metal-dielectric boundaries. In contrast to SIMS, SCM data are not influenced by the angle and energy windows of an analyser. However, the sample current measurements provide lower dynamic range of the signal registration than SIMS, and SCM is applicable only to the structures with different secondary electron emission properties and/or different conductivity of the layers. To increase the efficiency, SCM should be accompanied by SIMS measurements or predetermined by proper calibration using other elemental-sensitive techniques.  相似文献   

2.
Secondary ion mass spectrometry (SIMS) employing an SF5+ polyatomic primary ion source was used to depth profile through poly(methylmethacrylate) (PMMA), poly(lactic acid) (PLA) and polystyrene (PS) thin films at a series of temperatures from −125 °C to 150 °C. It was found that for PMMA, reduced temperature analysis produced depth profiles with increased secondary ion stability and reduced interfacial widths as compared to analysis at ambient temperature. Atomic force microscopy (AFM) images indicated that this improvement in interfacial width may be related to a decrease in sputter-induced topography. Depth profiling at higher temperatures was typically correlated with increased sputter rates. However, the improvements in interfacial widths and overall secondary ion stability were not as prevalent as was observed at low temperature. For PLA, improvements in signal intensities were observed at low temperatures, yet there was no significant change in secondary ion stability, interface widths or sputter rates. High temperatures yielded a significant decrease in secondary ion stability of the resulting profiles. PS films showed rapid degradation of characteristic secondary ion signals under all temperatures examined.  相似文献   

3.
The azimuthal and polar angle distribution of Ni+ and Mo+ ions emitted from an ordered Ni4 Mo single crystal irradiated with 10-keV Ar+ ions was studied. Different azimuthal distributions for Ni+ and Mo+ ions emitted from the (001) Ni4Mo face were detected; emission maxima were observed in 〈 011 〉 and 〈 001 〉 directions for Ni+ and Mo+ ions, respectively. It was shown that polar distributions of nickel’s secondary ions vary with its energy. The observed systematic features were explained by correlated collisions in the upper layers of a Ni4Mo single crystal.  相似文献   

4.
The surface layer of an equiatomic TiNi alloy, which exhibits the shape memory effect in the martensitic state, is modified with high-dose implantation of 65-keV N+ ions (the implantation dose is varied from 1017 to 1018 ions/cm2). TiNi samples are implanted by N+, Ni+-N+, and Mo+-W+ ions at a dose of 1017–1018 cm−2 and studied by Rutherford backscattering, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction (glancing geometry), and by measuring the nanohardness and the elastic modulus. A Ni+ concentration peak is detected between two maxima in the depth profile of the N+ ion concentration. X-ray diffraction (glancing geometry) of TiNi samples implanted by Ni+ and N+ ions shows the formation of the TiNi (B2), TiN, and Ni3N phases. In the initial state, the elastic modulus of the samples is E = 56 GPa at a hardness of H = 2.13 ± 0.30 GPa (at a depth of 150 nm). After double implantation by Ni+-N+ and W+-Mo+ ions, the hardness of the TiNi samples is ∼2.78 ± 0.95 GPa at a depth of 150 nm and 4.95 ± 2.25 GPa at a depth of 50 nm; the elastic modulus is 59 GPa. Annealing of the samples at 550°C leads to an increase in the hardness to 4.44 ± 1.45 GPa and a sharp increase in the elastic modulus to 236 ± 39 GPa. A correlation between the elemental composition, microstructure, shape memory effect, and mechanical properties of the near-surface layer in TiNi is found.  相似文献   

5.
Ge x Si1 − x layers are investigated by means of secondary ion mass spectrometry (SIMS). Experimental results obtained with the use of a TOF-SIMS 5 instrument are presented. To surmount the so-called matrix effect, SIMS analysis is performed by using complex secondary ions: Ge2, CsGe+, and Cs2Ge+.  相似文献   

6.
A series of carbon-coated magnetic recording disks proved ideal for exploring sampling depth and ion formation trends as a function of variations in energy and cluster size (Aux) of the primary ion beam, and variations in over coat thickness and type. Ion yield from the underlying metal layer increased with increasing energy and decreasing cluster size of the primary ions. The yields varied nearly linearly with over layer thickness. In contrast, MxCsy depth profiles were unaffected by changes in the primary ion. The samples were fortuitously dosed with dinonyl phthalate, allowing a study similar to prior GSIMS work [I.S. Gilmore, M.P. Seah, J.E. Johnstone, in: A. Benninghoven, P. Bertrand, H.-N. Migeon, H.W. Werner (Eds.), Proceedings of the 12th International Conference on SIMS, Elsevier, Brussels, 2000, p. 801]. Ions prominent in the EI mass spectrum, including even electron ions, were more consistently enhanced at lower energies and higher cluster sizes than the primary (M + H)+ ion. The total secondary ion count was inversely proportional to the film thickness. Secondary electrons, largely originating in the buried metal layer, may be inducing organic ion formation [A.M. Spool, Surf. Interface Anal. 36 (2004) 264].  相似文献   

7.
The mass spectra of the residual gas in a metallic vacuum chamber of capacity 3 l are studied with an MI-9303 high-resolution magnetic resonance mass spectrometer in the mass range 1–140 u. The experiments are carried out under four evacuation conditions in the pressure range P = 10−8–10−10 Torr, and almost all the mass peaks forming multiplets are resolved. It is shown that the multiplets with mass numbers M≤80 have, as a rule, a multicomponent structure and hydrogen is the basic component responsible for the total pressure in the chamber irrespective of evacuation conditions. Next in order of intensity in the mass spectra are, CH 4 + , H2O+, CO+, and CO 2 + peaks. Other lines in the residual gas spectra are largely due to various C-, H-, N-, and O-based compounds. In addition, the background mass spectrum involves Cl-and F-based compounds and noble gas isotopes. The multiplets with M > 80 often degenerate into a single hydrocarbon line.  相似文献   

8.
Secondary ion mass spectrometry (SIMS) employing an SF5+ polyatomic primary ion source was utilized to analyze several materials commonly used in drug-eluting stents (DES). Poly(ethylene-co-vinyl acetate) (PEVA), poly(lactic-co-glycolic acid) (PLGA) and various poly(urethanes) were successfully depth profiled using SF5+ bombardment. The resultant molecular depth profiles obtained from these polymeric films showed very little degradation in molecular signal as a function of increasing SF5+ primary ion dose when experiments were performed at low temperatures (signal was maintained for doses up to ∼5 × 1015 ions/cm2). Temperature was determined to be an important parameter in both the success of the depth profiles and the mass spectral analysis of the polymers. In addition to the pristine polymer films, paclitaxel (drug released in Taxus™ stent) containing PLGA films were also characterized, where it was confirmed that both drug and polymer signals could be monitored as a function of depth at lower paclitaxel concentrations (10 wt%).  相似文献   

9.
The mass spectrum is calculated for those dileptons which are produced in the early phase of a heavy ion collisions via the direct production NN → l+lX and via the Compton process GN → l+lX with prompt gluons radiated in preceding NN interactions. Both mechanisms produce a mass spectrum which decreases steeply with invariant mass of the l+l pair and which is below the CERES data for Pb-Au collisions by about one order of magnitude. Received: 1 December 1999 / Revised version: 18 February 2000  相似文献   

10.
The formation of Ni x Al y intermetallic compounds in two-layer (Ni/Al) structures (nickel films deposited on aluminum substrates in vacuum) under bombardment by Ar+ ions has been studied experimentally. The method based on Rutherford backscattering of He+ ions is used to demonstrate that argon ion bombardment causes the formation of intermetallic compounds in the near-surface layer. The thickness of the intermetallic layer formed in the near-surface region substantially exceeds the projective ion path. The composition and thickness of the intermetallic layer depend mainly on the implantation dose and the substrate temperature, rather than on the ion current density. In the intermetallic layer, the content of nickel increases with increasing temperature. It has been established that, in the absence of bombardment, intermetallic phases are not observed at temperatures lower than T = 400°C and that, in the presence of bombardment, the Ni3Al intermetallic layer arises at a temperature of 320°C.  相似文献   

11.
Secondary ion species of silicon oxide films have been investigated using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Characterization of thermally grown SiO2 films on silicon has been performed. A diagram showing secondary ion spectra of SiO2 films in both positive and negative polarities indicates the pattern of change in polarities and intensities of ion species from SiO+ to Si5O11. The ions mostly change from positive to negative polarity between SinO2n−1 and SinO2n. Ion peaks with the strongest intensities in the respective cluster ions correspond to the SinO2n+1 negative ion. Intensities of ion species of SinO2n+2 appear negligibly small. Ion species of Si3O+, Si3O2+ and Si3O3+ have been found at the interface between silicon and SiO2 films. The intensity patterns of these ion species compared to those of SiO2 films indicate that most of these species are not emitted from the SiO2 films, but likely from the SiO structures.  相似文献   

12.
The Raman spectra of the α, γ, and smectic modifications of isotactic polypropylene (PP) are studied. The most significant spectral differences are observed in the frequency range around 2960 cm−1 for the spectral doublet assigned to the asymmetric stretching vibrations of the CH3 groups and in the frequency range around 800 cm−1, which is used for analysis of the phase composition of isotactic PP. It is demonstrated that the peak positions and relative intensities of the doublet assigned to the asymmetric stretching vibrations of the CH3 groups can be used to identify the polymorph modifications of isotactic PP.  相似文献   

13.
《Applied Surface Science》1986,25(4):391-400
The potential use of thin silicon nitroxide films as gate dielectrics in VLSI MOS devices has motivated much recent work. The present study shows that positive ion bombardment, as encountered in sputter depth profiling or ion implantation, can induce considerable movement of nitrogen in thin thermal oxide films on silicon. Low energy N+2 implants are performed in-situ in a SIMS apparatus and are subsequently depth profiled. The effect of implant dose and oxide thickness are examined and comparisons are made to films prepared by rapid thermal nitridation and LPCVD. Profiles obtained under O+2, O-, and Cs+ bombardment are also compared. SIMS depth profiles of implanted 200 Å oxides using positive ion bombardment show a depletion of nitrogen near the surface, a shoulder in the nitrogen concentration near the Si-SiO2 interface, and a peak in this concentration at the interface. Negative ion bombardment did not induce a shoulder-peak structure at the interface. The implications of these results are discussed.  相似文献   

14.
The prospects for SIMS three-dimensional analysis of biological materials were explored using model multilayer structures. The samples were analyzed in a ToF-SIMS spectrometer equipped with a 20 keV buckminsterfullerene (C60+) ion source. Molecular depth information was acquired using a C60+ ion beam to etch through the multilayer structures at specified time intervals. Subsequent to each individual erosion cycle, static SIMS spectra were recorded using a pulsed C60+ ion probe. Molecular intensities in sequential mass spectra were monitored as a function of primary ion fluence. The resulting depth information was used to characterize C60+ bombardment of biological materials. Specifically, molecular depth profile studies involving dehydrated dipalmitoyl-phosphatidylcholine (DPPC) organic films indicate that cell membrane lipid materials do not experience significant chemical damage when bombarded with C60+ ion fluences greater than 1015 ions/cm2. Moreover, depth profile analyses of DPPC-sucrose frozen multilayer structures suggest that biomolecule information can be uncovered after the C60+ sputter removal of a 20 nm overlayer with no appreciable loss of underlying molecular signal. The experimental results support the potential for three-dimensional molecular mapping of biological materials using cluster SIMS.  相似文献   

15.
The characteristics of high current amorphous silicon diodes   总被引:1,自引:0,他引:1  
Amorphous siliconpn junctions with various doping profiles have been prepared by the glow discharge technique and the effect of the barrier profile on electrical properties investigated. Current densities of up to 40 A cm−2 with rectification ratios of 104–105 were obtained withn +−ν−p + structures. The diode quality factor has also been investigated, both in the dark and under illumination.  相似文献   

16.
Secondary-ion mass spectroscopy (SIMS) is a hydrogen, isotope and compound sensitive analytical technique of extremely high absolute sensitivity. Continuing earlier measurements for carboxylic acids, adsorbed alcohols etc., we have carried out a systematical investigation of secondary-ion emission from metal-supported amino acids, containing various functional groups (e.g., alanine, phenylalanine, cysteine, arginine). In order to avoid damage effects we applied extremely small primary-ion current densities in the 10−9 A·cm−2 range. The main results of our investigations can be summarized as follows:
–  - All investigated amino acids produce high-intensity secondary-ion parent peaks (M+1)+ and (M−1).
–  - In addition positive as well as negative fragment ions representative for the different functional groups are emitted with high yields.
–  - For 2.5 keV Ar+-ions the absolute yields for the parent ions and the most important fragment ions are in the range of 0.1; the damage cross section is >10−14 cm2 for all investigated acids. The resulting absolute sensitivities are below 10−6 of one monomolecular layer or <10−12 g.
  相似文献   

17.
《Surface science》1986,177(1):229-237
The analyzing depth in a low-energy SIMS measurement has been studied on a nickel deposited (50 Å) copper single crystal by measuring inter-diffusion coefficients at various temperatures. The analyzing depth of this specimen under 0.7 keV, 1.2 μA/cm2 Ar+ ion bombardment was evaluated to be less than 9 Å, taking into consideration a mean distance of the diffused atoms. Taking account of these results, low-energy SIMS could obtain more accurate and intrinsic depth profiles with a depth resolution of about two or three atomic layers.  相似文献   

18.
The effects of C60 cluster ion beam bombardment in sputter depth profiling of inorganic-organic hybrid multiple nm thin films were studied. The dependence of SIMS depth profiles on sputter ion species such as 500 eV Cs+, 10 keV C60+, 20 keV C602+ and 30 keV C603+ was investigated to study the effect of cluster ion bombardment on depth resolution, sputtering yield, damage accumulation, and sampling depth.  相似文献   

19.
V Ganesan  K S Girirajan 《Pramana》1988,30(4):331-336
The temperature variation of the Debye-Waller factors of Cs+ and Cl ions in CsCl powder has been studied using X-ray powder diffraction. A continuous flow cryostat has been used to record the diffractograms and the integrated intensities of the Bragg peaks at different temperatures have been obtained. The integrated intensities of the odd and even reflections have been analysed following the structure of the CsCl compound and the Debye-Waller factors of the Cs+ and Cl ions have been estimated. The results have been verified by structure factor least squares refinement. Theoretical shell model lattice dynamical calculations have been done using a 7-parameter model in the harmonic approximation and the values compared with the present X-ray measurements.  相似文献   

20.
The results of investigating the wear resistance of E110 alloy samples irradiated by a He+ + Ar+ beam with a wide energy spectrum are presented. Surface modification under irradiation by an Ar+ beam at doses higher than 2 × 1018 ion/cm2 is shown to cause substantial enhancement of the wear resistance of samples because the structural homogeneity of near surface layers increases, the surface roughness decreases, and its microhardness increases. The application of a mechanical-geometrical wear model based on the experimental wear characteristics determined during accelerated tests indicates that the thinning of an alloy cladding can reach rates of 10−6–10−3 mm/s, which agree satisfactorily with data obtained in other simulation experiments. The presence of an oxide film changes a wear process characterized by an abrasive component.  相似文献   

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