Gamma Irradiation of Silicon. III. Levels in p-Type Material

Abstract

⁶⁰Co gamma irradiation of p‐type silicon produces donors in the lower half of the forbidden gap. From the temperature dependence of the electrical properties, a level 0.35 eV above the valence band was located for the case of silicon pulled from silica crucibles. For the case of float‐zone silicon, two levels 0.21 and 0.28 eV above the valence band were found. The 0.35‐eV level is introduced at the rate of 10⁻⁴ net donors/cm³ per photons/cm². The introduction rate for the 0.21‐eV level is lower than that for the 0.35 level, and that for the 0.27‐eV level is so low that it was difficult to measure.