Respectfully, I am quite familiar with this subject matter. You might have a silver PVD coated slide, as do I on various firearms, but DLC is carbon based and is always a shade of black. DLC can be thought of as a subset of Physical Vapor Deposition, using carbon rather than various metals.
That's incorrect. Nothing in carbon mandates that it be black. Look at a diamond. Look at dry ice. It has to
do with the electron configuration of the carbon atom in the structure.
Diamond has carbon in an sp3 electron bond configuration, which places the bandgap in the UV, which is why it appears clear. Graphite has carbon in sp2, with a very low bandgap, underneath that of the IR. That's why it is absorptive and looks black.
DLC films contain carbon in a mix between sp3 and sp2 states, hence the name diamond-like. Therefore, the bandgap of the film, and thus the wavelength where it stops being transparent can be varied by controlling the ratio between these two states.
Further, DLC films are not necessarily PVD, but can be deposited via CVD from organic precursors. This is the preferred method for higher quality.
I think your experience in DLC is within bulk metalworking, where you want it thick and cheap. This is totally different from the work done on DLC in optics and solid-state devices where thin films are deposited in a tightly controlled process.
Carbon is a very versatile element that can crystallize in the forms of diamond or graphite. There are many noncrystalline carbons, known as amorphous…
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