engleski

Divacancies at room temperature in germanium

We have studied the annealing of vacancy defects in neutron and proton irradiated germanium. After neutron irradiation the Sb-doped samples were annealed at 473, 673 and 773 K for 30 min. The positron lifetime was measured as a function of temperature (30 – 295 K). A lifetime component of 330 ps with no temperature dependence is observed in as irradiated samples, identified as the positron lifetime in a neutral divacancy. The average positron lifetime in the samples annealed at 473 K has a definite temperature dependence, suggesting that the divacancies become negative as the crystal recovers and the Fermi level moves upward in the band gap. Proton irradiation of germanium at 37 K with subsequent room temperature annealing also resulted in a similar lifetime component 315 ps, in good agreement with the neutron irradiation experiment.

divacancy ; point defect ; germanium ; positron annihilation spectroscopy

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