Effect of hydrogen and nitrogen incorporation on the properties of tetrahedral amorphous carbon films grown using S bend filtered cathodic vacuum arc process

摘要

The electrical and mechanical properties of as- grown and also hydrogen and nitrogen incorporated tetrahedral amorphous carbon (ta-C) films, deposited using S bend filtered cathodic vacuum arc process have been reported. First, the effect of varying negative substrate bias on the dark conductivity (? D), activation energy (?E?) and residual stress of as grown ta-C films and next the effect of varying hydrogen and nitrogen partial pressure on the properties of ta-C: H and ta-C: N films deposited at a high negative substrate bias of -300V are reported. The value of ? D is minimum at 10?? ohm ?1cm?1 in as- grown ta-C films deposited at -150V substrate bias whereas the value of ?E? is maximum at 0.22 eV and residual stress is maximum at 0.71 GPa in as- grown ta-C films deposited at -200 V applied substrate bias and it is found to depend on the substrate bias. Hydrogen incorporation in ta-C films decreases the value of ? D to 1.0×10??ohm ?1cm?1, increases the values of ?E? to 0.45 eV continuously with the increase of hydrogen partial pressure up to 1.4×10?3 mbar whereas nitrogen incorporation in ta-C films increases the value of ? D to 10?1 ohm?1cm?1 and decreases the value of ?E? to 0.07 eV continuously with the increase of nitrogen content up to 16.3 at. %. Low amount of hydrogen incorporation in ta-C films up to 7.4×10??mbar hydrogen partial pressure reduces the value of residual stress and larger amount of hydrogen incorporation beyond this pressure increases the value of residual stress whereas nitrogen incorporation in ta-C films reduces the values of residual stress. The effect of hydrogen on ta-C is to give a modest gain in semi-conducting properties by passivating some defect states whereas the effect of nitrogen gives n-type doping effect in ta-C films.