from 28 June 2015 to 3 July 2015 (Africa/Johannesburg)
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SAIP2015 Proceeding published on 17 July 2016
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Ultra smooth surface of diamonds, towards Å scale roughness for the (111) orientation

Presented by Prof. Simon CONNELL on 30 Jun 2015 from 16:10 to 18:00
Type: Poster Presentation
Session: Poster1
Track: Track A - Division for Physics of Condensed Matter and Materials
Board #: A.451

Abstract

Synthetic diamond of exceptional quality is required for many high technology applications. We mention two examples: δ-doped diamond as an electrical switch in FETs, expected to operate at high power and high frequencies; and 111-oriented diamond plates that are needed at synchrotrons such as the ESRF to serve as beam splitter monochromators working in reflection geometry (Bragg case). The surface is of special interest. It should be smooth, flat and defect free. For the diffraction application, the requirements is in addition a low miscut for the 111 surface,. In this paper, we present a summary of the different polishing techniques as well as their advantages and limits: - Mechanical polishing with nano diamond powder. - Oxygen electron cyclotron resonance etching, oxygen radio frequency etching or microwave etching in a O<sub>2</sub>+SF<sub>6</sub>+Ar gas mixture. - Oxygen implantation, followed by annealing in vacuum at 950 °C. ‘‘Lift-off’’ resulted from either a hydrogen plasma or an acid etch, and the final anneal in air at 500 °C provided an additional soft isotropic etch. - Hot metalling: the diamond is moved with low speeds over a surface of pure Fe at 1000oC in vacuum for at least 3 hours - Mechanical diamond-grit-less sciafe polishing at high speeds, high temperatures and high loads, The best results include a surface with a roughness less than 2Å (rms) level over 10x10µm2 areas as measured by AFM and optical profiling, for the (111) surface orientation. The polished diamonds were then carefully quality checked by X-ray diffraction synchrotron topography at beamline BM05, at the ESRF, France, in order to visualize defects in the crystals caused by the surface damage from the polishing process.

Award

No

Level

PhD

Supervisor

SH Connell (UJ)

Paper

Yes

Permission

Yes

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