Halogen impurities in CdS and ZnSe single crystals by thermal neutron activation

Abstract

Halogen donors (chlorine, bromine and iodine) in cadmium sulfide and zinc selenide single crystals (vapor grown platelets with and without halogen dopants) were determined by thermal neutron activation analysis. This approach proved to be simple, rapid and highly selective. The analyzed impurity contents range from 100 ppb to several ppm. Radionuclides used for identification of chlorine, bromide and iodine were 38Cl ( t 1/2 ≈ 25 min), 82Br ( t 1/2 ≈35·1 hr) and 128I ( t 1/2 ≈ 25 min), respectively; these nuclides were radiochemically isolated and measured by gamma scintillation spectrometry. The levels of the impurities measured by this method were then used to identify new types of donor-acceptor pair line spectra and two-electron transitions accociated with chlorine, bromine or iodine impurities. The results were all in good agreement with the suspected lines, and accordingly well characterized.