AN ELECTRON-PARAMAGNETIC-RESONANCE AND MAGNETOOPTICAL STUDY OF VANADIUM IN ZNXCD1-XTE-V

The vanadium-related defects in high-resistivity Bridgman-grown ZnxCd1 -xTe (x = 0.04, 0.10) crystals have been studied by electron paramagne tic resonance (EPR) and magnetic circular dichroism absorption spectro scopy (MCDA). Only one vanadium-related spectrum is observed by EPR, w hich is attributed to a V2+ defect in orthorhombic point symmetry. Its spin Hamiltonian parameters are electron spin S = 3/2, Lande 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 x 10(-4) cm(-1), A(yy) = -57 x 10(-4) cm(-1) A(zz) = -65 x 10(-4) cm(-1) with the principal axes x, y, z or iented along the [110], [001], [-110] directions respectively. The MCD A measurements performed on the same crystals show in addition to the absorption bands of the V2+ ion those of the V3+ ion, a defect not obs erved by EPR; the non-observation of the V3+ EPR spectrum is ascribed to a strong zero-field splitting of the (3)A(2) groundstate. The low p oint symmetry of the V2+ defect is attributed to the formation of V-Cd -X(Cd) second nearest neighbour complexes in the Zn-alloyed CdTe sampl es.