DEFECTS IN PHOTOREFRACTIVE CDTEV - AN ELECTRON-PARAMAGNETIC-RESONANCESTUDY

Vanadium-doped CdTe has recently been shown to have a high sensitivity for optical processing at 1.5 mum but the role of the vanadium dopant has been questioned- We present the results of an electron paramagnet ic resonance study of this material, which demonstrates that vanadium is the dominant paramagnetic defect, which pins the Fermi level and gi ves rise to photoconductivity at 1.5 mum. The vanadium is substitution ally incorporated on a Cd site at concentrations of almost-equal-to 5 X 10(16) cm-3 and acts as a deep donor with a 2+/3+ level at E(v)+0.8 eV. The defect is only observed in the 3+ charge state. The spin Hamil tonian parameters of the V3+ defect are determined as follows: electro n spin S=1, Lande g-factor g=1.962+/-0.001, central hyperfine interact ion constant A=60X10(-4) cm-1, Cd Ligand hyperfine interaction constan t T=4X10(-4) cm-1.