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

The Hartree-Fock cluster procedure was used to obtain the associated electr onic distributions for F-19* (I = 5/2, E-x = 197 keV excited nuclear state of the F-19 atom) at possible sites in crystalline Si, Ge and diamond and t o calculate nuclear quadrupole coupling constants nu(Q) and the asymmetry p arameter eta of the electric field gradient at the modelled sites. Lattice relaxation effects have been incorporated by employing a geometry optimizat ion method to obtain minimum energy configurations for the clusters modelli ng each site. The intrabond (IB), antibonding (AB) and substitutional (S) s ites in the bulk and the atop site on the surface were studied. From a comp arison with nu(Q) and eta values observed in time differential perturbed an gular distribution (TDPAD) measurements we were able to identify the high f requency component in Si and Ge with F-19* at the intrabond site. In diamon d two high frequency components are observed. These are identified with F-1 9* at intrabond and substitutional sites. For the low frequency site in Si and Ge the assignment is made to F-19* implants at dangling bonds in the bu lk resulting from implantation damage. In diamond none of the sites studied could provide lower frequency nuclear quadrupole parameters close to the o bserved ones.