Energy Dependence of Damage Recovery inn-Type Ge Electron-Irradiated at 4.2°K

Abstract

Damage produced in $n$-type Ge by electron irradiation partially anneals in two stages centered near 35 and 65°K. A small but constant reduction in conductivity is produced by bombardment with electrons with energies from 0.7 to 1.2 MeV. The fraction of the radiation-induced conductivity change recovered in each stage is observed as a function of electron energy for a sample with little residual damage and for one with large residual damage. The 65°K defect recovery increases with energy in both cases. This result is explained on the basis of radiation modification of 65°K defects. The 35°K defect recovery versus energy peaks in both cases. The dropoff at low energy is explained as being due to radiation annealing. The dropoff at high energies is explained as being due to the decrease in the modification of 65°K defects to 35°K defects in the sample with little residual damage. In the sample with considerable residual damage it is suggested that production of 35°K defects as primary defects decreases with increasing energy. Results are consistent with the model proposed by MacKay and Klontz with the addition that the 65°K defect can be modified to the 35°K defect by ionization of one of the two electrons trapped by the 65°K defect.