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First diamond films grown by Cardiff Diamond Foundry

Monday 14th January 2013

A Microwave plasma inside the new microwave plasma chemical vapour deposition system at Cardiff.

A Microwave plasma inside the new microwave plasma chemical vapour deposition system at Cardiff. The white/lilac region is a plasma at approximately 3000 C where as underneath it lies a silicon wafer upon which diamond is growing at 800 C.

The newly established Microwave Plasma Chemical Vapour Deposition (CVD) facilities at Cardiff University have grown their first films of Nanocrystalline Diamond. Several films have been grown with thicknesses varying from 30nm to 1µm. These films are now being characterised at the Diamond Light Source by glancing angle X-ray Diffraction.

The films were grown by Dr Oliver Williams and his PhD student, Evan Thomas, using CVD under low pressures. In this process methane gas diluted with hydrogen is activated by microwave energy to very high gas temperatures (3000 K) in a plasma. This plasma contains a complex mixture of hydrocarbons and atomic hydrogen. At the edge of this plasma, the carbon containing species condense into diamond. The atomic hydrogen etches back any non-diamond carbon so high purity diamond can be grown. Diamond is generally grown at 800 C but can be grown below 400 C at a reduced growth rate.

Nanocrystalline diamond has many diverse applications. The extreme mechanical properties make it an ideal material for Nano/Micro-Electro-Mechanical Systems. Its low friction and wear properties make it an advanced tribological coating. The surface stability, chemical inertness and electrochemical properties are currently being exploited for bio-sensing. The thermal conductivity properties are being investigated as a next generation insulator for silicon CMOS electronics.

nanocrystalline diamond film

Example of a nanocrystalline diamond film grown on silicon. This particular film is around 150nm thick, taking around 40 minutes to grow at 850 C.