Radiation Defects Created by Co60 γ‐Rays in p‐ and n‐Type Si of High Purity

Radiation defects created by γ‐irradiation of Co60 at 300 °K in high purity p‐Si (ϱ = 5 × 103 to 4 × 104 Ω cm) and n‐Si (ϱ = 440 to 5 × 103 Ω cm) are investigated by measurements of Hall effect and minority carrier lifetime. The oxygen concentrations in Si are in the range of 5 × 1014 to 5 × 1015 cm−3; compensation of electrically active impurities is low. It is shown that defects in high purity Si created at 300 °K are divacancies and complexes of vacancies with donor or acceptor impurities. Divacancies introduced by γ‐irradiation are not the primary defects. They become predominant after “exhaustion” of the dopant. When divacancies become the predominant defects the Fermi level occupies its limit position Ev + 0.390 eV in the gap. At low doses (Φ < 1016 photons/cm2 vacancy‐impurity complexes and at heavy doses (Φ > 1017 photons/cm2 divacancies play the main role in the recombination process.