The sub-surface region of chemical vapour deposition (CVD) diamond was
transformed by C+ ion implantation followed by isochronal annealing up to 1200
oC. Different implantation regimes and with different energies at different implantation
temperatures would give different thicknesses were studied. This enabled a
study in the evolution of the stiffness of the damaged layer as a function of annealing.
The technique of choice for this study was the non-destructive Brillouin light
scattering (BLS) utilizing two scattering geometries; indirectly scattered phonons
(Kr¨uger-type geometry) for temperature anneals up to 600 oC, and the conventional
surface ripple mechanism up to 1200 oC. It has been argued that surface acoustic
waves (SAW) on a transparent medium are enhanced by applying a thin metallic
reflective layer on the surface, this study has showed that opacity of the substrate
is key. In fact, bulk modes with SAW-like characteristics emanating from indirect
photon scattering off phonons after reflection at the smooth reflective back of the
sample dominated down to transmission below 5% which was observed after annealing
between 500-600 oC (low annealing temperatures). The other complementing
techniques employed to understand the changing structure of the ion implanted
diamond were Raman spectroscopy, electromagnetic transmission in the visible
range, electron energy loss spectroscopy (EELS) and high-resolution transmission
electron microscopy (HRTEM) in addition to theoretical techniques: transport of
ions in matter (TRIM), finite element modelling (FEM) and elastodynamic Green’s
functions. Although the electronic techniques showed a structurally changing material
at the low annealing temperatures, the optical ones did not show significant
changes in the ion-damaged material possibly due to lack of distinct interface between
the pristine diamond and the ion irradiated region at these lower annealing
temperatures.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/19301 |
| Date | January 2016 |
| Creators | Motochi, Isaac |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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