The concentration of nitrogen and oxygen in semiconductor silicon and their solubilities in silicon at its melting point have been measured by charged particle activation analysis and infrared spectrophotometry. It has been found that: (i) commercial semiconductor silicon contains less than 1×1015 normalatoms/cm3 of nitrogen in the un‐ionized state; (ii) the solubility in solid silicon is 4.5±1.0×1015 normalatoms/cm3 for nitrogen and 2.75±0.15×1018 normalatoms/cm3 for oxygen; and (iii) the solubility in liquid silicon is about 6×1018 normalatoms/cm3 for nitrogen and 2.20±0.15×1018 normalatoms/cm3 for oxygen. Thus, the equilibrium distribution coefficient has been determined to be about 7×10−4 for nitrogen and 1.25±0.17 for oxygen. The solubilities of the two elements are compared with those of other elements, especially carbon, and are discussed thermochemically.

The concentration of carbon in semiconductor silicon and the behavior of carbon in the fusion and crystallization of silicon have been studied by the use of charged particle activation analysis. The solubility of carbon in solid silicon has been found to be 3.5×1017 normalat./cm3 or slightly less at the melting point, and the equilibrium distribution coefficient of carbon between solid and liquid silicon has been determined to be 0.07±0.01 . Carbon content over the above solubility value has seldom been observed in silicon single crystals produced by modern industrial techniques. The content appears to depend more on the growth conditions of the single crystal than on the chemical purification method. The phase diagram of the C‐Si system in the extremely low carbon concentration range is given, together with a discussion of the kinematics of the carbon behavior in zone melting. Also, a new technique for studying the evaporation of carbon from the silicon melt is shown.

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