Annealing-induced positron trapping in Cu2O single crystals

Abstract The positron lifetime spectrum of Cu 2 O single crystals annealed under reducing conditions, exhibits a long-lived component of about 238 ps. The presence of a luminescence band at 0.74 μ m suggests that this component is due to positrons trapped in oxygen vacancies. Positron trapping in copper vacancies is not observed in thse crystals. On the basis of the results a value of (174±5) ps is proposed for the positron lifetime in the Cu 2 O bulk, and a lifetime of about 320 ps for positrons trapped in V Cu − − V O + pairs.