Transparent nanocrystalline diamond coatings and devices
A method for coating a substrate comprises producing a plasma ball using a microwave plasma source in the presence of a mixture of gases. The plasma ball has a diameter. The plasma ball is disposed at a first distance from the substrate and the substrate is maintained at a first temperature. The plasma ball is maintained at the first distance from the substrate, and a diamond coating is deposited on the substrate. The diamond coating has a thickness. Furthermore, the diamond coating has an optical transparency of greater than about 80%. The diamond coating can include nanocrystalline diamond. The microwave plasma source can have a frequency of about 915 MHz.
1. A method for coating a substrate, comprising:
producing a plasma ball using a microwave plasma source in the presence of a mixture of gases, the plasma ball having a diameter;
disposing the plasma ball at a first distance above the substrate such that the plasma ball does not contact the substrate, the substrate maintained at a first temperature of less than 400 degrees Celsius; and
maintaining the plasma ball at the first distance from the substrate for a first time;
depositing a diamond coating on the substrate, the diamond coating having a thickness,
wherein, the diamond coating has an optical transparency of greater than about 80 percent.
2. The method of claim 1 , wherein the diamond coating includes nanocrystalline diamond.
3. The method of claim 1 , wherein the substrate and/or thin film has a thickness less than a thickness threshold, the thickness enabling the substrate to have an optical transparency of greater than 80%.
4. The method of claim 3 , wherein the substrate includes at least one of gallium nitride, aluminum gallium nitride, gallium arsenide, germanium, silicon, silicon nitride and silicon carbide.
5. The method of claim 1 , wherein the microwave plasma source has a frequency of about 915 MHz.
6. The method of claim 1 , wherein the diameter of the plasma ball is the range of about 15 cms to about 30 cms.
7. The method of claim 1 , wherein the first distance is about 0.1 mm to about 5 mm.
8. The method of claim 1 , wherein the first time is about 20 minutes to about 60 minutes.
9. The method of claim 1 , wherein the thickness of the diamond coating is in the range of about 30 nm to about 150 nm.