Annealing of Radiation Defects in Semiconductors

Abstract

Radiation induced defects studied through changes in conductivity and Hall coefficient have been observed to anneal in a number of different temperature ranges. Only those processes occurring above 80°K and involving defects created by electron irradiation have been considered in this paper. It has been found that the first annealing process in n-type germanium occurs at about 50°C and is structure sensitive, apparently to the original chemical donor impurity. Higher temperature annealing processes, observed at about 200°C and previously interpreted as due to direct annihilation of vacancies and interstitials must also be sensitive to other crystal defects. In p-type germanium there is a process of rearrangement of a defect center at about 200°K, exhibiting first order kinetics, but with a time constant which is strongly dependent upon the charge state of the defect. At about 120°C the defects in p type apparently anneal out completely, in striking contrast to the n-type case. Less extensive silicon measurements, showing lifetime recovery between 200 and 400°C again indicate through their kinetics the importance of other impurities or defects in the annealing process.