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- Author or Editor: T. Shigematsu x
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Abstract
The charged particle activation analysis of ultra-trace carbon in boron-doped silicon with the12C(d,n)13N reaction has been developed. In order to apply13N substoichiometric separation to determine carbon in silicon, we studied the rapid dissolution of silicon using nitric acid as the13N carrier. Its amounts were as small and definite as possible and the nitrogen oxide gas produced during the dissolution was collected. Silicon was dissolved for 6 min in a mixture of hydrofluoric acid, acetic acid and phosphoric acid, which contained potassium nitrate as the13N carrier and nitrogen oxide was collected in the sodium hydroxide solution. In order to combine the dissolution method with13N substoichiometric separation, the conditions for steam distillation as pre-separation were also refined in relation to increases in the amount of carrier. Nitrogen-13 was separated substoichiometrically after silicon dissolution and steam distillation. This analytical procedure was used to determine carbon in boron-doped CZ–Si. Carbon at 0.7–12.7·1015 atoms/cm3 was determined with good reproducibility. It took less than 30 min to start the radioactivity measurement after the end of iradiation. The detection limit was 2·1013 atoms/cm3 (0.2 ppb).
Abstract
The effectiveness of charged particle (alpha) activation analysis in determining the content of ion-implanted boron on the surface of Si wafers and the doped boron in epitaxially grown Si film and SiO2 film was evaluated. The method was found to be accurate and precise if interference from surface contamination and the matrix were accounted for and an appropriate standardization method was used.
Abstract
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.
Abstract
The radiochemical separation of nitrogen was studied for the determination of ultra trace carbon in gallium arsenide by deutron activation analysis using the12C/d, n/13N reaction. It is based on steam distillation as ammonia and successive substoichiometric precipitation as ammonium tetraphenylborate. It was found that the decontamination factors of coexistent elements such as72Ga,76As and11Co to13N are enough large to determine carbon as low as 1 ppb in gallium arsenide.
Abstract
A method of radioactivation analysis has been developed for the determination of indium and tin. It is based on substoichiometric extraction of indium diethyldithiocarbamate into carbon tetrachloride from a slightly ammoniacal solution in the presence of potassium cyanide. With this method, indium can be determined via116m In (T=54 min) and tin via113m In (T=104 min) which is formed by the reaction112Sn(n, ψ)113Sn. The method has been applied to the determination of indium in metallic zinc and of tin in tin-doped gallium arsenide, and 0.4 ppb of indium was analyzed in a zinc sample.
Abstract
Ultra trace carbon in gallium arsenide has been determined by deuteron activation analysis. It consists of steam distillation of nitrogen as ammonia and successive substoichiometric precipitation as ammonium tetraphenylborate. It is confirmed that nitrogen is precipitated substoichiometrically as ammonium tetraphenylborate in spite of the various chemical species of13N. The procedure developed was applied to the deuteron activation analysis of carbon in carbon-doped and undoped gallium arsenides. It took 30 minutes from the end of irradiation to the start of the radioactivity measurement. The detection limit of carbon in gallium arsenide was as low as 1 ppb.
Abstract
Oxygen in silicon was determined by the secondary nuclear reactions of6Li(n, α)T and16O(t, n)18F. Lithium fluoride was deposited in vacuum on fused quartz, covered with the sample and irradiated in a nuclear reactor. The depth profiles of18F in fused quartz and in silicon were observed, and enough depth to eliminate surface oxygen was estimated. On the basis of these results, oxygen was determined by the average cross-section method. Oxygen concentration in CZ silicon with various growing condition was 5–26 ppm and was consistent with those determined by the infrared absorption method. The detection limit of oxygen in silicon is 5 ppm.
Abstract
A method of radioactivation analysis has been developed for the determination of chromium. It is based on the substoichiometric extraction of chromium diethyldithio-carbamate into methyl-isobutyl-ketone from acetate buffer solution in the presence of EDTA and potassium cyanide. The method has been applied for the determination of chromium in high-purity calcium carbonate and NBS glasses as standard reference materials.
Abstract
We have developed charged particle activation analysis to determine light elements at a sub-ppb level. This analytical method is characterized by sample bombardment with charged particles at a few tens of mA and substoichiometric separation for13N,11C and18F within two half-life times and with decontamination factors of more than 108. Nuclear reactor interference is also estimated with this method. This analytical method is confirmed to be useful for characterizing highly purified materials from analytical results for boron, carbon, nitrogen and oxygen in Nb refined by the floating zone melting method.
Abstract
In order to determine iron on silicon wafer surface at a level of 1014 atoms·m–2 the efficiency of a well-type Ge detector for59Fe 
-ray emissions was measured and a low temperature silicon direct bonding technique was developed. With silicon direct bonding at a temperature of 350 to 650°C iron remains near the interface of the bound silicon. The iron contamination of the interface escaped from the interface can be ignored with this technique. The value of iron obtained was (2.7 to 5.9)·1014 atoms · m–2 in the surface on silicon wafers.
