Some Effects of Fast Neutron Irradiation on Carrier Lifetimes in Silicon

Single crystal specimens of silicon have been exposed to fast neutrons from a reactor source to determine the room temperature effects of irradiation on carrier lifetimes. For highly n‐ and p‐type material the approximate lifetime damage constants, defined as ${\text{1/τ=1/τ}}_i\mathrm{+\alpha \phi }$ , are found to be α_n=4.4×10⁻⁷ (nvt)⁻¹ × (sec)⁻¹ and α_p=1.2×10⁻⁶ (nvt)⁻¹ (sec)⁻¹. Two possible positions of the dominant recombination level are 0.36 ev below the conduction band or 0.33 ev above the valence band. Further agreement with the value of α_p has been obtained by measuring high level lifetime in silicon junction diodes.