ControlControl of residual stress of tetrahedral amorphous carbon thin film deposited on dielectric material by filtered cathodic vacuum arc source by using mid-frequency pulse bias voltage

• June 2018
• Surface and Coatings Technology 349
• 📷Jung-Hwan In
• Young-Bok Kim
• Yeon Hwang
• 📷Ju H Choi of residual stress of tetrahedral amorphous carbon t...
• Stress is mainly caused by ion peening (compressive stress) and some atomic rearrangement towards structure of higher atomic packing density and with some desorption mechanisms- for instance H2- (causing tensile stress).
• Therefore, internal stress is not necessarily linked to sp3 content
• To be observed that contrary to elder popular belief, the sp3/sp2 content cannot be easily determined with Raman spectroscopy, considering that similar so-called D peak corresponds either to sp2 cluster symmetric A edge vibration (at ~1350cm-1) - incorrectly named "D disorder" peak , or to sp3 subdomains ( at ~1330cm-1) which is the D diamond peak. In both cases -if no internal stress is shifting these peaks).
• Optimization of optical properties of harder and more stable ta-C can only be achieved if the material did not undergone some thermal graphitic degradation process (reducing much the optoelectronic gap) and when considering some sp3 atomic rearrangement caused by quantum electronic activation ( for instance with hard UV and with release of chemical recombination energy and several other catalytic and activation effects).
• Interpretation of produced measurements and conclusion have therefore to be relativised and questioned to some extent.