Portal de Periódicos da CAPES

Structure of the self-interstitial in diamond

2004; American Physical Society; Volume: 69; Issue: 4 Linguagem: Inglês

10.1103/physrevb.69.045203

1550-235X

Hannah E. Smith, Gordon Davies, Mark E. Newton, H. Kanda,

Electronic and Structural Properties of Oxides

We report on a study of the structure of the neutral self-interstitial ${\mathrm{I}}^{0}$ in diamond, through the use of uniaxial stress measurements and isotope-substitution effects on the optical absorption lines near 1685 and 1859 meV. The stress perturbations are explicable in terms of a center with ${D}_{2d}$ symmetry, and the dominant stress-induced perturbations are found to be interactions between the states of the center. The interstate couplings establish that the excited electronic state of the transitions is a doublet, of $5.0\ifmmode\pm\else\textpm\fi{}0.1\mathrm{meV}$ splitting, revealing the existence of another electronic state at ${\mathrm{I}}^{0}$ that has not been discussed within existing models of the center. The excited-state doublet couples through ${B}_{2}$ deformations, while the well-known ground-state doublet, whose splitting is measured spectroscopically at $7.6\ifmmode\pm\else\textpm\fi{}0.1\mathrm{meV},$ is coupled by ${B}_{1}$ deformations of the center. The data are quantitatively consistent with ${\mathrm{I}}^{0},$ in its ground electronic state, tunneling rapidly in a ${B}_{1}$ vibrational mode between equivalent ${D}_{2}$-symmetry configurations, and in its excited electronic state tunneling in a ${B}_{2}$ mode between equivalent ${C}_{2v}$-symmetry configurations; in both cases, the motion is sufficiently rapid for ${\mathrm{I}}^{0}$ to have the observed effective ${D}_{2d}$ point group.