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

Vanadium-doped CdTe has recently been shown to have a high sensitivity for optical processing at 1.5 μm but the role of the vanadium dopant has been questioned. We present the results of an electron paramagnetic resonance study of this material, which demonstrates that vanadium is the dominant paramagnetic defect, which pins the Fermi level and gives rise to photoconductivity at 1.5 μm. The vanadium is substitutionally incorporated on a Cd site at concentrations of ≊5×1016 cm−3 and acts as a deep donor with a 2+/3+ level at Ev+0.8 eV. The defect is only observed in the 3+ charge state. The spin Hamiltonian parameters of the V3+ defect are determined as follows: electron spin S=1, Landé g-factor g=1.962±0.001, central hyperfine interaction constant A=60×10−4 cm−1, Cd Ligand hyperfine interaction constant T=4×10−4 cm−1.

Magnetic circular dichroism (MCD) is demonstrated to allow the simultaneous characterization of the V2+ and Vs ions in vanadium-doped Bridgman grown CdTe bulk samples. The identification of the MCD bands relies on the analysis of nand ptype co-doped samples as well as on spectroscopic aiyuiiiciwa n u ~~c ~~w i i l j i a u v ~~ UI LIIC: suciiyui VI G ~I L Q I ~I I VI U, uaiius wiui uie U-' concentrations determined by electron paramagnetic resonance spectroscopy allowed the calibration of our spectra for V3+. Based on photo-MCD experiments, we also provide a calibration of MCD bands related to V+. Finally, the pP]/[V3t]ratio can be derived simply from the shape of the MCD spectrum in the low-energy region (E c 1.1 eV).

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