“…Some studies reported that the dominant existence of Al in Al-DLC is the Al–O bonds, probably because of the O-incorporated impurities in the deposition chamber or exposure in the air. , Recently, a few reports have said that Al–C bonds could form more easily than Al–Al bonds in the Al-DLC films during PVD. , Some studies have confirmed that Al atoms solid-dissolve into the carbon matrix or form amorphous Al nanoparticles, which present Al-enriched stripes or blocks in transition electronic microscopy images. , Now, there is dispute about the surface roughness evolution of Al-DLCs with the Al-doping content. , Even more, there is no convincing reason why an Al-enriched stripe or block forms in Al-DLC films and no nano-crystallite of Al forms in DLC with more than 20 at. % Al . It is necessary to study the Al existence states of Al atoms in DLC films from an atomistic scale.…”