Spectroscopic characterization of photorefractive CdTe:Ge

We report on the photoabsorption, magnetic circular dichroism (MCD) and electron paramagnetic resonance (EPR) of Ge-doped CdTe. Strong photoinduced absorption changes have been detected for two samples at ambient and low temperatures (down to 4.3 K). They reveal the existence of four absorption bands around 0.94, 1.10, 1.22 and 1.36 eV at 4.3 K. MCD experiments at: 1.4 K allowed the tagging of different paramagnetic defects to the two bands at lower energies. EPR demonstrated that one of them is Ge-Cd(+). We propose that the second one is an isolated or Ge-related A-centre. A diagram showing the various transport processes is given. (C) 1999 Elsevier Science B.V. All rights reserved.