A large number of complex defects were seen in natural and synthetic diamonds, but it was not known whether they form during growth or as a result of later processes. An understanding of diffusion profiles of the dopant impurities was crucial for design of electronic devices. Theoretical studies were made here of migration processes for several complexes including N, H and vacancies in diamond, to find out how they form. First-principles density functional calculations were performed to study structural properties and the activation energies for migration of these defects. Migration paths were derived by constructing a set of several intermediate structures between two energy minima by linear interpolation. The effect of temperature on calculated barriers was described by including vibrational energy and entropy. It was found that the energy barrier for migration of interstitial hydrogen between two bond-centred positions was 2.8eV. Also, hydrogen was readily trapped by both vacancies and by the N-V complex. Energies liberated in these reactions were 5.5 and 5.8eV, respectively.

Theoretical Study of Migration Processes in Bulk Diamond. Butorac, B., Mainwood, A.: Diamond and Related Materials, 2008, 17[7-10], 1225-8