The electronic structure of interstitial zinc in its two T-d sites in ZnSe

We report ODEPR measurements in ZnSe which lead to the identification of (Z n-i)(Zn)(+), i.e., the interstitial zinc located at the T-d Site surrounded by four Zn atoms. Its central Zn-67 hyperfine interaction (1425 MHz) is is otropic and is significantly larger than that previously determined for (Zn -i)(Se)(+) (1088 MHz), indicating that the unpaired electron is more highly localized on (Zn-i)(Zn)(+). A "point-ion" envelope wave-function analysis which also takes into account the hyperfine interaction of the Se-77 atoms, in conjunction with other considerations, places the second donor level ( / + +) position for (Zn-i)(Se) and(Zn-i)(Zn) at similar to 1.0 and 1.6 eV below the conduction band respectively, with approximate error bars of +/-0 .3 eV. Our experimental results are in good agreement with state-of-the-art ab initio calculations. (C) 1999 Elsevier Science B.V. All rights reserved .