Kinetics of defect formation and defect structure in copper-doped CdI2 crystals

S.A.Pyroha, S.Metry*, I.D.Olekseyuk, I.V.Kityk**

Lesya Ukrainka Volyn` University, 13 Voli Ave., 43009 Lutsk, Ukraine *Institute of Physics, Lemans University, 2 Semandra boul., Leman, France **Physics Institute, Pedagogic University, 13/15 Armii Krajowej Al., PL-42201 Czestochova, Poland

Received December 22, 1997; in final form, May 30, 1998

Using EPR technique, two crystallographically non-equivalent paramagnetic copper centers having two orientations each have been revealed in both intentionally non-doped and copper-doped CdI2 single crystals. The paramagnetic center generation kinetics has been studied during high-temperature annealing (T = 420 K). The paramagnetic centers arise due to decay of complexes including a copper atom in the cadmium sublattice and a vacancy in the iodine one. Two center generation mechanisms have been found: the direct recharging of the centers and their long-range interaction through the crystal phonon subsystem. The crystal illumination at 420 K accelerates the reverse process, i.e., formation of complexes. Equations are derived describing the variation kinetics of the paramagnetic center concentration in the crystal.

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