Effect of Co concentration on the structural, optical and magnetic properties of CoxZn1−xTe thin films grown by electron beam evaporation

Abstract

In the present work, CoxZn1−xTe (x = 0.0, 0.03, 0.05 and 0.08) thin films were prepared by the commercially viable electron beam evaporation technique with an aim to understand the effect of Co concentration on its structural, optical and magnetic properties. X-ray diffraction reveals that the films retain the cubic zinc blende phase of ZnTe for all the Co concentrations. X-ray photoelectron spectroscopy confirms the substitutional occupancy of Co in ZnTe host lattice. The optical band gap of these doped semiconducting thin films could be tuned from 2.21 eV to 1.73 eV by changing the Co concentration. The red emission ~1.85 eV observed in the photoluminescence spectroscopy confirms the tetrahedral bonded Co2+ ions in ZnTe lattice. The ferromagnetic behaviour exhibited by these doped thin films can be attributed to the presence of intrinsic defects as well as to the carrier induced ferromagnetism.