Accession Number : AD0654685

Title :   DETERMINATION OF CARBON, NITROGEN AND OXYGEN IN SILICON BY ACTIVATION ANALYSIS,

Corporate Author : CONTROLS FOR RADIATION INC CAMBRIDGE MASS

Personal Author(s) : Kegel,Gunter H. R.

Report Date : APR 1967

Pagination or Media Count : 84

Abstract : Methods of determining impurities in silicon by activation analysis are reviewed. Impurities considered are carbon, nitrogen and oxygen with concentrations in the parts-per-million range. Non destructive techniques only are considered. Prompt reactions are unsuitable for these elements in the specified concentration range because the surfaces of the silicon samples will be contaminated by adsorption of impurities from the air. Reaction products should be sufficiently long lived to allow removal of adsorbed impurities between irradiation and measurement. Slow neutron and gamma irradiations lead to excessive matrix activation and therefore are not applicable. The same holds for irradiation with tritons obtained from the reaction Li6(n,alpha)t. Fast neutron activation yields reaction products with too short a mean life. The successful application of charged particle activation has been described in the literature; sensitivities below 1 ppm have been reported. These publications are reviewed. Methods for measuring positron activities in the presence of a gamma-ray background are described. A weighted least-squares-fit procedure for analysing composite decay curves is given. (Author)

Descriptors :   (*SILICON, *RADIOACTIVATION ANALYSIS), (*CARBON, RADIOACTIVATION ANALYSIS), (*NITROGEN, RADIOACTIVATION ANALYSIS), (*OXYGEN, RADIOACTIVATION ANALYSIS), NEUTRON ACTIVATION, IMPURITIES, DETERMINATION, NONDESTRUCTIVE TESTING, GAMMA RAYS, POSITRONS

Subject Categories : Radiation and Nuclear Chemistry
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE