EPR and ODMR investigations of defect centres in ZnTe:Cl

Abstract

We report EPR and ODMR (optically detected EPR) studies of Cl doped ZnTe that show a fraction of the chlorine participating in complex, deep-level defects. Photoexcitation at T < 50 K creates an EPR spectrum corresponding to an S = 12 centre with nearly isotropic g factor (g = 1.96) and hyperfine interaction with a Cl nucleus. Weak, satellite EPR lines correspond to interaction with three equivalent Te nuclei and a low abundance, I = 12 nucleus X, which could be either an Sn, Pb or Cd nucleus. Our model for this trigonal symmetry defect is a Cl on a Te site with X on a neighbouring Zn site. ODMR studies at 2 K of an emission band peaking near 770 nm gives the Cl centre EPR spectrum and in addition the spectrum of a trigonal acceptor centre with highly anisotropic g-tensor (g″ = 2.65, g⊥ ≅ 0). The ODMR work shows that the 770 nm emission results from recombination of the electron of the deep Cl centre with the hole of the trigonal acceptor centre.