Locations of implanted ¹⁹F* atoms in Si, Ge and diamond studied through their nuclear quadrupole interactions

Abstract

The Hartree-Fock cluster procedure was used to obtain the associated electronic distributions for ¹⁹F^* (I = 5/2, E^x = 197 KeV excited nuclear state of the ¹⁹F atom) at possible sites in crystalline Si, Ge and diamond and to calculate nuclear quadrupole coupling constants v _Q and the asymmetry parameter η of the electric field gradient at the modelled sites. Lattice relaxation effects have been incorporated by employing a geometry optimization method to obtain minimum energy configurations for the clusters modelling each site. The intrabond (IB), antibonding (AB) and substitutional (S) sites in the bulk and the atop site on the surface were studied. From a comparison with v _Q and η values observed in time differential perturbed angular distribution (TDPAD) measurements we were able to identify the high frequency component in Si and Ge with ¹⁹F^* at the intrabond site. In diamond two high frequency components are observed. These are identified with ¹⁹F^* at intrabond and substitutional sites. For the low frequency site in Si and Ge the assignment is made to ¹⁹F^* implants at dangling bonds in the bulk resulting from implantation damage. In diamond none of the sites studied could provide lower frequency nuclear quadrupole parameters close to the observed ones.