D'Haenens-Johansson, Ulrika F. S. (2011) Optical and magnetic resonance studies of point defects in CVD diamond. PhD thesis, University of Warwick.

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Abstract

This thesis reports research conducted on point defects in single crystal diamond
utilising the complementary techniques of electron paramagnetic resonance
(EPR), optical absorption and photoluminescence (PL) spectroscopy. Intentional
silicon-doping of chemical vapour deposition (CVD) diamond allowed the production
of samples grown on differently oriented substrates and containing distinct
silicon isotopic abundances.
The EPR spectrum of the neutral charge state of the silicon split-vacancy centre
in diamond, (Si-V)0, has been characterised in the literature. Evidence for the
assignment of the 1.31 eV zero phonon line (ZPL) seen in absorption and PL to
the 3A2g -> 3A1u transition arising at (Si-V)0 is presented. Reversible charge transfer
between the negatively charged centre, (Si-V)− (ZPL at 1.68 eV), and (Si-V)0
enabled the determination of calibration factors relating defect concentrations to
their respective ZPL intensities. Preferential alignment of trigonal centres, such as
(Si-V), in CVD material grown on {110}-substrates has been observed. The formation
of (Si-V) centres during CVD synthesis and via irradiation and annealing
of silicon-doped diamond was studied.
Variable temperature EPR spectroscopy under illumination was used to investigate
the optical spin polarisation (SP) of the (Si-V)0 3A2g ground state. Two
different mechanisms for the SP are considered; selective intersystem crossing of
(Si-V)0, and photoionisation of (Si-V)−. The properties of (Si-V)0 are compared
to those of the extensively studied negatively charged nitrogen vacancy centre,
(N-V)−. The effective spin-lattice relaxation and spin polarisation rates for both
centres during continuous illumination are explored using pulsed EPR methods.
A new defect, labelledWAR3, with spin S = 1
2 was observed in silicon-doped diamond
and characterised using multifrequency EPR. Analysis of the data revealed
that WAR3 is the neutral charge state of a silicon divacancy complex decorated
by a hydrogen atom, (Si-V2:H)0. The experimentally derived 29Si and 1H hyperfine parameters are in good agreement with the values calculated using the spindensity-
functional technique, confirming this model and ruling out a non-planar
structure.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QC Physics
Library of Congress Subject Headings (LCSH):	Point defects, Diamond crystals, Chemical vapor deposition
Official Date:	April 2011
Dates:	Date Event April 2011 Submitted
Institution:	University of Warwick
Theses Department:	Department of Physics
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Newton, M. E. (Mark E.)
Sponsors:	Diamond Trading Company ; Engineering and Physical Sciences Research Council (EPSRC)
Extent:	xxii, 217 leaves : ill., charts
Language:	eng

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