Abstract
Synthetic single-crystal diamonds grown by microwave-assisted chemical vapour deposition have been investigated using optical spectroscopy. Absorption, photoluminescence and cathodoluminescence have been utilised to obtain optical spectra of the diamonds in the ultraviolet, visible and infrared regions, in order to characterise point defects present in the crystals. Temperature dependence measurements, isotopic substitution and thermal annealing have been used to characterise the atomic constituents of defects. Application of a uniaxial stress to oriented samples has allowed the symmetries of a number of point defects to be determined; in particular, defect centres with zero-phonon lines (ZPLs) at 466.6 nm (2.657 eV), 467.2 nm (2.654 eV), 496.8 nm (2.495 eV), 532.7 nm (2.327 eV) and 562.5 nm (2.204 eV) have been determined to have rhombic I, rhombic I, rhombic I, monoclinic I and monoclinic I or rhombic I symmetries, respectively.The 466.6, 496.8 and 562.5 nm ZPLs demonstrate a preferential orientation along the crystallographic axes, which is potentially characteristic of the growth process. Atomic configurations are proposed for these centres. The 467.2 nm transition is proposed as originating from an atomically perturbed version of the 466.6 nm centre. A calibration factor for the silicon-vacancy defect centre (with ZPL at 736.8 nm (1.682 eV)) has been determined. Studies of nitrogen-15 doped samples have unambiguously confirmed the direct involvement of nitrogen in a number of new and previously investigated ZPLs.
Chapter one introduces the project and outlines the objectives. Chapter two introduces the basic relevant theoretical background. Chapter three details the experimental methods utilised. Chapter four is concerned with the general optical characterisation of single-crystal CVD diamonds. Chapter five presents data on the preferentially oriented centres. Chapter six discusses a number of other defect centres investigated and some further characterisations. Chapter seven concludes the work and discusses suggestions for future investigation.
| Date of Award | 28 Apr 2009 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Alan Collins (Supervisor) |