Defects in photorefractive CdTe:V: An electron paramagnetic resonance study

Abstract

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.