Isoelectronic Oxygen Trap in ZnTe

Abstract

An optical transition at 1.986 eV in ZnTe has earlier been attributed to the radiative recombination of an electron-hole pair bound at an oxygen atom substituting isoelectronically for Te. In this paper the results of isotopic substitution and Zeeman experiments are offered to prove the correctness of this identification. Crystals of ZnTe grown in the presence of An${\mathrm{O}}^{18}$ exhibit an isotope shift of the $B(J=2)$ line 0.45\ifmmode\pm\else\textpm\fi{}0.05 meV to higher energies. At 1.7\ifmmode^\circ\else\textdegree\fi{}K, this is observed both for the no-phonon line and its LO phonon replicas. Zeeman analysis of the $J=2$ quintet shows that the impurity center has the cubic symmetry of the ZnTe zinc-blende lattice, and is therefore a point defect. The dominant character of the $B$-line emission is found to be forced electric dipole, produced by the magnetic field mixing of $B(J=2)$ and $A(J=1)$ states.