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The vanadium-related defects in high-resistivity Bridgman-grown Zn x Cd 1−x Te (x = 0.04, 0.10) crystals have been studied by electron paramagnetic resonance (EPR) and magnetic circular dichroism absorption spectroscopy (MCDA). Only one vanadium-related spectrum is observed by EPR, which is attributed to a V 2+ defect in orthorhombic point symmetry. Its spin Hamiltonian parameters are electron spin S = 3/2, Land é g-tensor g xx = 1.976, g yy = 1.959, g zz = 1.974, crystal field splitting parameters D = −0.933 cm −1 and E = −0.073 cm −1 , nuclear spin I = 7/2, hyperfine tensor A xx = −65 × 10 −4 cm −1 , A yy = −57 × 10 −4 cm −1 , A zz = −65 × 10 −4 cm −1 with the principal axes x , y, z oriented along the [110] , [001], [−110] directions respectively. The MCDA measurements performed on the same crystals show in addition to the absorption bands of the V 2+ ion those of the V 3+ ion, a defect not observed by EPR; the non-observation of the V 3+ EPR spectrum is ascribed to a strong zero-field splitting of the 3 A 2 groundstate. The low point symmetry of the V 2+ defect is attributed to the formation of V Cd -X Cd second nearest neighbour complexes in the Zn-alloyed CdTe samples.

A quantitative electron paramagnetic resonance (EPR) study of vanadium-related defects in semi-insulating and co-doped p-type and n-type bulk CdTe:V shows the Vcd donor to be the dominant electrically and optically active 4 x l O I 5 c m 3 for the defect, determined by quantitative EPR spectroscopy, is in agreement with the value obtained from photorefractive measurements on the same crystals. A comparison of the total V content with the Vcd donor concentration indicates the existence of additional V-related defects no! observed in EPR. Surprisingly the neutral donor state, v"& is not observed by EPR in the n-type material. No other V-related defects were detected in the n-or p-type material.defect ifi semi-ifisu!s!ifig photor&&ve fia!eria!, The effectitye traF &fisi!y of

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