Neutron activation analysis of impurities in gallium phosphide

Gallium phosphide is a new type of semiconductor material. Although this substance becomes highly radioactive after neutron irradiation, because of the nature of its component elements (gallium and phophorus) the chances were that the great sensitivity of the neutron activation technique would at least partly solve this very difficult trace analysis problem. The possibilities of non-destructive analysis of long lived elements (Co, Sb, Sc, Zn, Fe...) were investigated first. To extend this method over the determination of medium-life elements, different methods of radiochemical separation plan were worked out. The method developed gives quantitative analysis of fourteen elements (Ag, As, Au, Ba, Co, Cr, Cu, Fe, Ir, Na, Rb, Sb, Sc, Zn) amounting very often to less than one ppb. (T.G.)