LATTICE SITES OF ION IMPLANTED Cu ATOMS IN DIAMOND

Radioactive Cu atoms were accelerated to 60 keV at the online isotope separator ISOLDE at CERN, and implanted into a type IIa natural diamond sample to a dose of 2 x 10 cm. The channeling of β particles and conversion electrons emitted in the decay of Cu and Zn*, respectively, were monitored about the three major axial directions with a two dimensional position-sensitive detector. The electron emission channeling data were collected from the room temperature implanted sample and after annealing at 1200 K. The observed channelling patterns were fitted with simulations based on the many beam formalism of electron motion through a crystal lattice. In the as-implanted sample, 25% of the Cu atoms were located a mean, isotropic displacement of 0.25(5) Å from substitutional sites, and the remainder, fR = 75%, at sites that gave an isotropic emission yield. Annealing at 1200 K results in enhanced axial and planar channeling effects. The fits to the data yield either a fraction f1= 43(5)% of Cu atoms located 0.22(4) Å from substitutional sites and fR = 57%, or a fraction f1= 10(2)% at substitutional sites, a fraction f2= 50(5) % at mean isotropic displacement of 0.5 Å from substitutional sites, and a ‘random’ fraction fR = 40%.