The DISCS project has taken three main objectives :
1. to deposit diamond and silicon carbide thin films using a range of CVD technologies;
2. to use advanced manufacturing techniques to process the diamond and silicon carbide films, e.g. using plasmas and ion beams;
3. to fabricate prototype, advanced sensing structures in the carbide thin films.
Diamond films have been deposited using thermal filament and microwave chemical vapour deposition (CVD) technologies. Deposition onto substrates up to 50 mm in diameter has been demonstrated.
In addition multilayer films have been grown of undoped and doped films using boron precursor gases as the dopant carrier. Selected area deposition of the films has also been demonstrated, especially in diamond technology. These results demonstrate that it is sensible to consider the fabrication of sensing structures of doped films.
Downstream processing of the films has demonstrated that it is possible to reactive ion beam etch the structures required to give a very high quality structure definition. Metal contacts to the films have also been formed in order to make an initial assessment of the electrical properties of the as deposited and subsequently machined materials.
The performances of the films at high temperatures is under investigation. Laser Raman, resistivity, capacitance and X-ray measurements have all been undertaken at elevated temperatures. Depending on the technique being used, temperatures up to 850 C have been used to collect data. The results, thus far, indicate that the films are of high quality. There is evidence to suggest that the properties of the films are affected by temperature. However, above a minimum temperature of approximately 350 C, the properties remain stable and reproducible. There is evidence to suggest that this stability is connected with the movement of minority species, such as hydrogen, within the films.
Funding Schemeundefined - undefined
OX11 0RA Didcot