The radiation hardness of pulled silicon doped with germanium

Abstract

The radiation hardness of Czochralski grown n-type silicon samples doped with germanium (NGe = 2×10²⁰ cm⁻³) and without it was investigated after irradiation by fast neutrons. The dependence of the effective carrier concentration on fluence was described in the framework of Gossick’s corrected model. It was found that doping the germanium impurity resulted in increase of n-Si radiation hardness. The isothermal annealing of n-Si 〈Ge〉 after fluence 1.4×10¹⁴ n⁰⋅cm⁻² was studied. It was shown that the annealing of defect clusters is caused by the annihilation of vacancy type defects in clusters with interstitial defects. For di-interstitial (Е₁ = 0.74 eV; ν₁ = 3.5×10⁶s⁻¹), silicon interstitial atom (Е₂ = 0.91 eV; ν₂ = 7×10⁶ s⁻¹) and vacancy (ЕV = 0.8 eV; ν = 1×10⁷s⁻¹) the migration energies and frequency factors were determined. During the storage at room temperature, the behaviour of defect levels Ec−0.17 eV and Ec−0.078 eV was studied in the samples of Si (DOFZ) and Si 〈Ge〉, correspondingly.