Helium-Temperature Annealing of Electron-Irradiatedn-Type Germanium

$n$-type germanium (4 × ${10}^{14}$ Sb/${\mathrm{cm}}^3$) has been irradiated with 1.1-MeV electrons at 5 °K. The defects produced have been studied by measuring the voltage-dependent capacitance of a metal-germanium junction formed at the surface of a germanium sample. These measurements were made at 10 °K and directly gave the charge density near the surface of the sample. The production and recovery of defects seen near the surface is the same as seen in bulk experiments. A 0.5-MeV electron beam was used to cause radiation annealing of the defects at 5 °K. The fraction recovered during radiation annealing is directly proportional to $t^{\frac{1}{2}}$. A model based on diffusion-limited-recovery theory is used to explain these results. This model is also used to discuss the results of previous experiments. The temperature dependence of the observed recovery at 5 °K gave a defect migration energy of 0.0044 ± 0.008 eV.