| 1. |
- Pinto, H., et al.
(författare)
-
First-principles studies of the effect of (001) surface terminations on the electronic properties of the negatively charged nitrogen-vacancy defect in diamond
- 2012
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 86:4
-
Tidskriftsartikel (refereegranskat)abstract
- Density functional calculations have been carried out on (001)-orientated slabs of diamond with different surface terminations. A negatively charged nitrogen-vacancy defect (NV-) is placed in the middle of the slab approximately 1 nm from each surface and the effect of the surface on the internal optical transition in NV- investigated. The calculations show that the chemical nature of the surface is important. We find that although the clean surface does not lead to charge transfer between the defect and the surface, there is a splitting of the empty excited state, the final state in optical absorption, arising from a strong hybridization of the surface and defect bands. This leads to a broadening of the 1.945-eV transition of the NV- defect. OH- and F-terminated surfaces have no surface states in the band gap and again charge transfer between the defect and surface does not occur. The splitting of the e levels responsible for the optical transitions for OH or F termination is similar to that found in periodic boundary condition simulations for bulk diamond where the defects are separated by 1 nm, and thus the calculations show that hydroxylated or fluorinated surfaces give favorable optical properties.
|
|
| 2. |
- Pinto, H., et al.
(författare)
-
On the diffusion of NV defects in diamond
- 2012
-
Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 209:9, s. 1765-1768
-
Tidskriftsartikel (refereegranskat)abstract
- Besides their importance for quantum information processing, NV defects are crucial agents for the diffusion and aggregation of nitrogen in diamond. In the absence of transition metals, it is thought that the first stage of nitrogen aggregation, where close neighbour nitrogen pairs are formed, is mediated by NV defects. Here we use density functional theory to explore the barriers to NV diffusion. We conclude that the barrier is around 5 eV when there is a ready source of vacancies and that this barrier is weakly dependent on pressure.
|
|
| 3. |
- Pinto, H., et al.
(författare)
-
Theory of the surface effects on the luminescence of the NV(-) defect in nanodiamond
- 2011
-
Ingår i: Physica Status Solidi (a) applications and materials science. - : Wiley. - 1862-6300 .- 1862-6319. ; 208:9, s. 2045-2050
-
Tidskriftsartikel (refereegranskat)abstract
- A vacancy with one of the carbon neighbours replaced by a nitrogen atom in diamond (the NV centre) is a defect of particular interest due to its many potential applications. In the negatively charged state, the defect is paramagnetic with spin 1 and under optical excitation it exhibits an intense luminescence with a zero-phonon line at 1.945eV. This fluorescence is found in nanodiamonds even as small as 5nm and an important question is the effect of the surface of the nanodiamond on the optical emission of NV-.Density functional calculations are used in this work to investigate the effect of the bare (001) and (001)-OH diamond surfaces on the electronic structure of NV-. We show that the (001)-OH diamond surface has the minimum interaction with the defect and is the ideal terminating surface of nanodiamonds, while the bare (001) diamond surface has a strong effect on broadening the emission.
|
|
