Colour centres on demand in diamond

• Main Author: Dale, Matthew W
• Format: Dissertation
• Language: English
• Published: University of Warwick 2015
• Subjects: QC Physics

This thesis reports research on point defects in single crystal synthetic diamond. A number of techniques have been used including electron paramagnetic resonance (EPR), infrared (IR) absorption, ultraviolet-visible (UV-Vis) absorption and photoluminescence (PL) spectroscopies. The effect of perturbations by uniaxial stress on defect formation and migration have been investigated. Photo- and thermo-chromic effects have been investigated in irradiated and annealed type-IaA diamond. Charge transfer between nitrogen and di-nitrogen vacancy defects together with quantification in their negative charge states has allowed their calibration constants to be determined. Improvements have been made in the 13C hyperfine parameters for N2V− and its observation in diamond of natural isotopic abundance has allowed its 14N quadrupole parameters to be determined. Defects in neutron irradiated diamond have been studied by annealing isochronally up to 1600 XC. The majority of nitrogen could be accounted for through all annealing stages in a variety of defects including a maximum of 72(7) ppm of NV−. The annealing behaviour strongly supports the involvement of interstitials in interstitial mediated nitrogen aggregation in addition to vacancy assisted nitrogen aggregation. A model of the mechanisms has been proposed and simulated with chemical kinetics, the result of which agrees well with experiment. The effect of applying up to 3.0 GPa (0 0 1) uniaxial stresses to type-IIa samples during electron irradiation has been investigated. The treatment caused very little preferential orientation of the single interstitial and nearest neighbour di-interstitial, however it caused significant preferential orientation of 3H, believed to be the next nearest neighbour di-interstitial. The production rate of both di-interstitials was also increased by stress. Irradiated samples have been annealed under [0 0 1] uniaxial stresses. The annealing successfully created preferentially oriented populations of the (0 0 1)-split self interstitial with up to 93(1)% efficiency. Preferentially oriented interstitials have been annealed in situ in an EPR spectrometer allowing the site populations to be determined throughout the anneal.