Diamond has several extreme properties such as the highest Youngs modulus, thermal conductivity, electrical resistivity of all materials etc, that make it very attractive for a plethora of applications ranging from cutting tools to single photon sources. Unfortunately, due to the phase diagram of carbon, diamond forms under pressures higher than 100K bar and temperatures greater 2000K within the Earth. These conditions have been reproduced under laboratory conditions but are almost impossible to scale up to the large areas required for many applications. Diamond remains one of the hardest materials to grow synthetically.
Chemical Vapour Deposition of diamond was first accomplished around the same time as high pressure synthesis. This technique dissociates hydrogen and methane under high temperature plasmas to create atomic hydrogen and methyl radicals. The methyl radical acts as a building block for diamond growth, with non-diamond carbon being suppressed by the extremely aggressive atomic hydrogen background. This is a metastable process that can be difficult to control. However, thin diamond films can now be produced on substrates such as silicon with Young’s modulus as high as 1100 GPa and with unrivalled high thermal conductivity.
In this work the production of high-quality diamond films for Micro-Electro-Mechanical Systems and Surface Acoustic Wave (SAW) devices will be demonstrated. Nucleation of diamond on foreign substrates, control over the CVD growth process, Chemical Mechanical Polishing and device fabrication will be discussed. Integration with materials such as AlN and GaN will be discussed as well as the production of single photon centres based on colour centres such as NV and SiV. Superconducting and non-superconducting MEMS / SAW devices will be demonstrated with frequency-Q products as high as 1014 Hz.