Impurity Dependence of Defect Introduction and Annealing in Electron Irradiated n-Type Germanium

Electron irradiation experiments on Si and Ge have indicated the creation of highly mobile interstitial atoms that in turn displace substitutional chemical impurity atoms (S) from the lattice; hence, the primary products of irradiation may be lattice vacancies (V) and interstitial chemical impurities (I). Subsequent annealing may then involve some type of interaction between (V) and (I). The relative amount of radiation damage, or ratio of (I) to the remaining substitutional chemical impurity atom concentration (SR), is also expected to be of importance since there may be competition during annealing between (I) and (SR) for the mobile (V). Samples of P, As, Sb, Sb-Ag, and Sb-Au doped n-type Ge of different initial carrier concentrations were irradiated at ~ 295°K with ~ 1.7 Mev electrons to different ratios of (I) to (SR), and electrical property measurements were made at 77°K immediately after irradiation. The results indicate (1) an increase in the apparent rate of removal of conduction electrons for material of higher initial carrier concentration, (2) a difference in the apparent rate of removal for different dopants, (3) a small dependence of the apparent removal rate on the total amount of disorder introduced, and (4) the amount of annealing was not a sensitive function of the ratio of (I) to (SR) for P or Sb-doped material, but was for As-doped material.