共查询到20条相似文献,搜索用时 14 毫秒
1.
T. Nozaki M. Iwamoto K. Usami K. Mukai A. Hiraiwa 《Journal of Radioanalytical and Nuclear Chemistry》1979,52(2):449-459
Oxygen in silicon nitride films on silicon wafers was analyzed by activation with the16O(3He, p)18F reaction. By3He bombardment of samples propertly arranged under consideration of the18F recoil effect, total oxygen was reliably determined and its predominant part was estimated to be located whether on film
surface, in film interior, or on film-substrate interface. Sample films with 0.1 to 2 μm thicknesses were found to contain
0.2 to 2 μg/cm2 of oxygen in locations varying with preparation conditions. This method has been compared with ESCA and other methods for
surface analysis. 相似文献
2.
K. Shikano H. Yonezawa T. Shigematsu 《Journal of Radioanalytical and Nuclear Chemistry》1996,207(2):413-423
Oxygen was determined in three kinds of ZrF4-based fluoride glass [ZrF4–BaF2–GdF3–AlF3 (ZBGA), ZrF4–BaF2–LaF3–YF3–AlF3–LiF–NaF (ZBLYALN) and ZrF4–BaF2–LaF3–YF3–AlF3–LiF (ZBLYAL)] used for fabricating optical fiberby18O(p, n)18F reaction without significant nuclear interference. The main long life96Nb nuclide was produced by the96Zr(p,n) reaction in a non-destructive analysis of ZBGA-fluoride glass and reduced by using a coincidence system with Ge(Li) and NaI(T1) detectors. Substoichiometric separation of18F was also used to determine oxygen in fluoride glass, especially in glass containing yttrium as a component element because the89Zr produced by the89Y(p,n) reaction is a positron emitter, the same as18F. It was confirmed that the oxygen concentration in fluoride glass was 13–2460 ppm related to the loss by scattering. 相似文献
3.
D. P. Chowdhury J. Arunachalam Rakesh Verma Sujit Pal S. Gangadharan 《Journal of Radioanalytical and Nuclear Chemistry》1992,158(2):463-470
40 MeV -particles have been used to determine oxygen impurity at ppm levels in silicon, copper, and stainless steel, through the radiochemical separation of18F from the matrix. The separation of18F has been carried out by two techniques, viz.(1) distillation of H2SiF6 and (2) precipitation of KBF4 and some modification has been applied in the separation, depending on the nature of interferences from the matrix. Instrumental approach was also carried out to determine the oxygen impurity at 100 ppm in Si matrix because this approach is not possible in Cu and stainless steel samples due to matrix activity. 相似文献
4.
A technique has been developed for oxygen depth profiling in a thickness range of 5 to about 100 mg cm−2 by activation with the16O(3He, p)18F reaction. An apparatus was set up for the activation of oxygen with a uniform probability along the depth, and a method
has been devised for step-wise etching of the activated sample. This technique has been applied to the study of oxygen behaviour
in heat treatment of silicon under various conditions. 相似文献
5.
The substoichiometric precipitation of fluoride with lanthanum was studied by using18F and140La tracers and it was found that fluoride could be precipitated substoichiometrically with lanthanum and the reaction ratio
between fluoride and lanthanum was 3∶1. The pH range at which fluoride can be separated substoichiometrically with lanthanum
is between 2 and 8. Barium and indium interfere in the precipitation of fluoride, sodium, copper and manganese, however, not.
Fluorosilicate can also be precipitated substoichiometrically by using lanthanum as a precipitant and the reaction ratio between
fluorosilicate and lanthanum was 1∶2. This separation was applied for the determination of oxygen in silicon crystals. The
concentration of oxygen measured in some silicon crystals was between 5 and 27 ppm and in good agreement with those by non-destructive
method and infrared spectrophotometry. 相似文献
6.
H. Gobrecht P. Brätter G. Willers S. Baum 《Journal of Radioanalytical and Nuclear Chemistry》1970,5(2):271-275
A sensitive method for determination of oxygen in selenium is described. Oxygen is converted into the gaseous compound sulfur
dioxide labelled with35S. The β-radiation of35S is measured by liquid scintillation counting. The detection limit is 0.02 ppm. The efficiency of vacuum distillation in
the purification of selenium, and the influence of air, dry oxygen and water on the absorption of oxygen by selenium have
been investigated. 相似文献
7.
Determination of isotopic composition of lithium by neutron activation analysis; comparison with mass spectrometry 总被引:1,自引:0,他引:1
An activation analysis method is described for routine determination of6Li-abundances in various lithium compounds on the basis of the reaction sequence6Li(n,α)T and16O(t, n)18F and the measurement of18F. Irradiations of diluted equeous solutions of samples containing CrO3 as internal flux monitor were carried out at a thermal neutron flux density of ϕ≤1011 n·cm−2·sec−1. Interferences from variations in neutron self-shielding oxygen concentration and triton range do not exceed 0.5% when using
the dilution technique. The results for6Li abundances from 3.52 to 7.60% with standard deviations of 1 to 2.5% were confirmed by mass spectrometric measurements. 相似文献
8.
G. Blondiaux C. S. Sastri M. Valladon J. L. Debrun 《Journal of Radioanalytical and Nuclear Chemistry》1980,56(1-2):163-171
During ion bombardment, thermal diffusion and radiation enhanced diffusion of atoms occur. These phenomena may be a source
of error in ion beam analysis, particularly in radioactivation analysis if contaminant surface atoms are present. It is shown
here that penetration of18F (derived from surface oxygen by nuclear reaction) in germanium single crystals, does not extend appreciably farther than
the maximum range of the recoiling18F nuclei. Since the analyzed depth is over an order of magnitude larger than the recoil, the validity of charged particle
activation analysis at the ppb level in the present case (oxygen→18F in germanium), is clearly demonstrated. 相似文献
9.
The activation of18O and19F by the reactions18O(γ, p)17N and19F(γ, 2p)17N was determined as a function of the maximum energy of the bremsstrahlung beam. By the use of this method it is possible
to measure oxygen or fluorine by counting the delayed neutrons emitted by17N with a half-life of 4.2 sec.
相似文献
10.
K. Shikano 《Journal of Radioanalytical and Nuclear Chemistry》1997,221(1-2):29-33
The rapid dissolution of silicon and the substoichiometric separation of18F were studied in order to determine nitrogen in a boron-doped silicon single crystal by activation analysis via15N(,n)18F. The silicon dissolution method was developed by using a nitric acid-based solution containing a known amount of ammonium fluoride, instead of hydrofluoric acid, as the18F carrier. The silicon could be dissolved to a depth of 100 m with a 10 mm Ø in 9 minutes. The conditions for18F steam distillation and substoichiometric precipitation as lanthanum fluoride were improved. 50% of the fluorine could be separated substoichiometrically even though the carrier amount was increased from 6–12 mmol to more than 16 mmol in order to add it to the dissolving solution. This dissolution method and improved substoichiometric separation were used to determine nitrogen in a boron-doped silicon single crystal. The nitrogen concentration was found to be less than the detection limit (50 ppb). 相似文献
11.
P. Kotas I. Obrusnik J. Kvitek V. Hnatowicz 《Journal of Radioanalytical and Nuclear Chemistry》1976,30(2):475-488
Diffusion of impurities is a basic operation in the technology of modern semiconductor devices especially integrated circuits.
A knowledge of diffusion parameters such as concentration profile, diffusion depth and diffusion coefficient makes the optimization
of a technological process possible. A destructive method of the step-by-step removal of the layers from the silicon single
crystal slices irradiated in a nuclear reactor with subsequent determination of impurity contents was used in the diffusion
studies of phosphorus, arsenic and gold. Phosphorus was determined by the beta counting of32P after a separation, arsenic and gold were determined by means of a Ge(Li) gamma-ray spectroscopy without any chemical separation.
The diffusion of boron was studied by the nondestructive method of the deconvolution of the energy spectrum of prompt alpha
radiation from10B(n, α)7Li after thermal neutron irradiation. 相似文献
12.
J. Giroux M. Talvat J. P. Thomas J. Tousset 《Journal of Radioanalytical and Nuclear Chemistry》1970,6(2):423-430
Activation analysis by charged particles may encounter great difficulties when ‘parasitic’ reactions induce in the matrix itself the same radionuclide as the one requested by the reaction for analytical aim. In this investigation we study reactions inducing18F activity in silicon and we show the importance of these reactions for determining low levels of oxygen in silicon by the reactions \(O\mathop \to \limits^\alpha {}^{18}F\) . For irradiations carried out with 54 MeV α-particles, the profile of18F production in silicon presents an activity decreasing very rapidly from the surface to depths of 500 μm without any connection with the \(O\mathop \to \limits^\alpha {}^{18}F\) activation curve. The diffusion of18F nuclides created at the surface from the oxide bed does not at all explain that result. The differences between these curves are attributed to parasitic reactions inducing18F activity in silicon. In order to confirm the reaction \(Si\mathop \to \limits^\alpha {}^{18}F\) we also investigated the profile of24Na and29Al production by another parasitic reaction in silicon. It is pointed out that the choice of incident energy is quite primordial, for analyses of oxygen in silicon with 54 MeV α-particles are not quite suitable. The best energy range appears to be around 35 MeV. 相似文献
13.
Classical activation analysis of fluorine by thermal neutrons has a limited application because of frequent interference from
chlorine, the short half life20F (11.4 s) and too high dead time of detectors. A procedure is described for fluorine determination using19F (n,p)19O reaction. Use of a boron carbide shield has no effect on the activity of19O (boron ratio −1) but considerably reduces background and interference due to18O (n, γ)19O reaction. The technique has been successfully applied to the determination of fluorine in organic compounds even in the
presence of large amounts of chlorine and oxygen. 相似文献
14.
Silicon as silicon dioxide in iron and steel-making slags and fluorspars was analyzed by 14 MeV neutron activation high-resolution
γ-ray spectrometry. Silicon was detected by measuring the 1.78 MeV γ-ray of28Al, the product of the28Si(n, p) reaction, using a 30 cm3 coaxial Ge(Li) detector. A modified TPA method was used for the calculation.28Al is also produced from phosphorus by the31P(n,α) reaction, and from aluminium by the27Al(n,γ) reaction. The contribution from the former reaction could be corrected experimentally when the P2O5 content of the sample was known, while the latter reaction could be neglected in this neutron energy region. The experimental
correction coefficient for phosphorus agreed well with the theoretical value calculated from the nuclear properties of silicon
and phosphorus. Yields of28Al from SiO2, P2O5 and Al2O3 of the same weight percentages were calculated as 1, 0.426 (experimentally 0.44) and 0.0022, respectively. The results of
this method agreed well with the results of the usual chemical methods. The limit of detection of SiO2 in iron and steel-making slags and fluorspars was calculated as 0.07%. The coefficient of variation of repeated experiments
was compared with the statistical one. 相似文献
15.
K. Shikano A. Mori M. Shimizu T. Ohtsuki H. Yuki K. Masumoto 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(2):211-216
Summary We have studied the photon activation analysis of carbon in InF3-based fluoride, chalcogenide and tellurite glasses for fiber amplifiers, and especially the nuclear interference from a matrix
produced by (γ,n), (γ,2n), (γ,p) and (n,γ) reactions and a flow method for the rapid and simple separation of 11C. A chemical separation technique is indispensable for determining carbon, because seventeen radionuclides are observed in
these glasses. The flow method can sequentially be undertaken, the fusion of an irradiated sample with an oxidizer, the conversion
of 11C into 11CO2, and the absorption of 11C in ethanolamine solution. We used a mixture of Pb3O4 and B2O3 as the oxidizer. There is interference with the 11C measurement because 18F and 68Ga are produced in fluoride and chalcogenide glasses by the 19F(γ,n), 23Na(γ,αn) and 69Ga(γ,n) reactions, respectively, and also absorbed in ethanolamine solution. Therefore, this flow method can only be applied
to tellurite glasses. The chemical yield provided by the flow method was close to 100% when determining carbon in Japanese
Iron and Steel Certified Reference Materials (JSS) by using lithium carbonate as a standard sample. We determined that the
carbon concentrations in four kinds of tellurite glass were 7 to 14 ppm. 相似文献
16.
A method has been developed for determining silicon in aluminium by fast neutron activation. It is based on the separation
of two gamma lines by a Ge(Li) detector: the 1.73 MeV line from the product of27Al(n, α)24Na and the 1.78 MeV line from the28Si(n, p)28Al reaction. In the case of aluminium-silicon alloys 100 μg silicon can be determined, with an error of 10% in an aluminium
sample of 1 g.
This work was supported in part by the International Atomic Energy Agency. 相似文献
17.
High utility value of charged-particle activation analysis is exemplified by the study on carbon, nitrogen and oxygen in semiconductor
silicon. A summary of the present authors' works is shown, and the equilibrium of carbon and oxygen in a silicon melt with
ambient carbon monoxide is discussed. Also, a note is given about the chemical separation of18F for the3He activation analysis of various matrices. 相似文献
18.
Particle induced X-ray emission analysis (PIXE) and nuclear reaction analysis have been applied to multielemental analysis
of human dental enamel in a proton microprobe. The PIXE technique was excercised for the characterization of multielemental
lateral distributions on and just below the sample surface. For the assessment of depth distributions of fluorine the resonant
nuclear reaction19F(p,aλ)16O was used. The combination of two analytical techniques comprising both atomic and nuclear interactions in a microprobe was
applied to enamel samples of different origins. One sample constituted a healthy enamel and the other one enamel from a restored
tooth. The microprobe in the combined mode was demonstrated to permit the establishment of lateral, concentration gradients
of elements heavier than phosphorus with a resolution of 15 μm in enamel and simultaneously of depth distributions of fluorine
better than 0.7 μm. The detection limits approached, 10–25 ppm for most of the elements considered.
Supported by the Swedish Natural Science Research Council 相似文献
19.
P. Bock Ch. Engelmann A. Hatterer 《Journal of Radioanalytical and Nuclear Chemistry》1977,38(1-2):97-106
Carbon and nitrogen are determined by means of the photonuclear reactions:12C(γ n)11C and14N(γ, n)13N. This article presents a simultaneous chemical separation method for the isolation of11C and13N. It is based mainly on combustion of the sample, after irradiation and etching, in a mixture of oxidising acid fused salts
(B2O3 and Pb3 O4) containing a dispersing agent (NaCl and KCl) and the respective carriers. Each analysis takes about 40 min altogether. Minimum
carbon and nitrogen contents of a few 10−2 μg·g−1 can be measured. The influence of the main competitive nuclear reactions on neighbouring elements, including the sodium itself,
is examined. 相似文献
20.
J. M. Calvert D. G. Lees D. J. Derry D. Barnes 《Journal of Radioanalytical and Nuclear Chemistry》1972,12(2):271-275
The various nuclear techniques which have been used to study oxygen self-diffusion in oxides are discussed. Results are given
for measurements using resonance capture in the18O(p, α)15N and18O(p, γ)19F reactions and the different techniques are compared. 相似文献