Diamond is not only the most expensive form of carbon in its purest natural form, but also an important material used in industry, where its extreme properties are without any equivalent. Diamond can be found in nature at high environmental cost or since the middle of the 20th century it can be produced artificially by reproducing the high-pressure and high-temperature conditions, which occur during its natural formation, or using the so called chemical vapour deposition (CVD) technique. Researchers in the MNB group use microwave plasma enhanced chemical vapour deposition (MWPECVD) reactors daily to carefully control the synthesis of artificial diamond layers. In this method, diamond is formed by the reaction at high temperature of chemical species from a carbon precursor, usually methane, created in a low pressure hydrogen plasma. Diamond layers can be deposited either as a thin (nano-crystalline diamond) or thick (micro-crystalline diamond) polycrystalline form, and monocrystalline (so called epitaxial diamond) form, which is the same as the form used for natural gems. Properties of CVD diamond layers are very sensitive to its synthesis conditions. Careful addition of minute amounts of impurities into the diamond lattice radically changes its properties with significant applications in optics, microelectronics, electrochemistry, etc. In particular, in the MNB group, diamond layers are grown with desired properties, via the addition of boron or phosphorus atoms. Understanding of boron and phosphorus doping of diamond is essential for the fabrication of basic components of future high power high voltage electronic devices. Heavily boron-doped diamond is a chemically stable, transparent (to some extent) and electrically conducting material for electrochemical or transparent electrode applications. The combination of the different MWPECVD reactors available in the MNB group has allowed the development of new processes and materials such as hard protective transparent diamond composite coatings with superior adhesion compared to conventional CVD diamond layers [MNB01], low temperature deposition of nano-crystalline diamond [MNB02], thick porous diamond layers [MNB03], boron-doped nano-crystalline diamond layers over large-area [MNB04], boron-doped epitaxial diamond layers [MNB05], etc.
[MNB01] A. Taylor et al., Synthesis and properties of diamond - silicon carbide composite layers, J. Alloys Compd. 800 (2019) 327-333 - DOI: 10.1016/j.jallcom.2019.06.016
[MNB02] A. Taylor et al., Novel high frequency pulsed MW-linear antenna plasma-chemistry: Routes towards large area, low pressure nanodiamond growth, Diam. Relat. Mater. 20 (2011) 613
[MNB03] V. Petrak et al., Fabrication of porous boron-doped diamond on SiO2 fiber templates, Carbon 114 (2017) 457 - DOI: 10.1016/j.carbon.2016.12.012
[MNB04] A. Taylor et al., Precursor gas composition optimisation for large area boron doped nano-crystalline diamond growth by MW-LA-PECVD, Carbon 128 (2018) 164 - DOI: 10.1016/j.carbon.2017.11.063
[MNB05] V. Mortet et al., Properties of boron-doped epitaxial diamond layers grown on (110) oriented single crystal substrates, Diam. Relat. Mater. 53 (2015) 29 - DOI: 10.1016/j.diamond.2015.01.006