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Regardless of used metal contact combinations, bulk-limited electrical behaviors were observed in metal/hydrogenated diamond-like carbon (DLC)/metal (MSM) devices through the study of I-V curves and temperature dependence of conductivity. For MSM devices with DLC deposited at a substrate bias of -50 V, the I-V curves exhibited ohmic electrical behaviors in the range of 0–1 V and followed the Poole-Frenkel mechanism in the range of 1–5 V. Moreover, the carrier transport was dominated by the thermally activated process with an activation energy of 0.1576 eV in the temperature range of 160–400 K. The bulk-limited behaviors of MSM devices could be attributed to the relatively high bulk resistance of the DLC layer. This result offers the fundamental insight into DLC based electrical devices and brings forward the concept to fabricate functional carbon based materials. [ABSTRACT FROM AUTHOR]

The electrical characteristics and spectroscopic properties have been comprehensively investigated in a DC superimposed high power impulse magnetron sputtering (DC-HiPIMS) deposition system in this paper. The influence of superimposed DC current on the variation of target and substrate current waveforms, active species and electron temperatures with pulse voltages are focused. The peak target currents in DC-HiPIMS are lower than in HiPIMS. The time scales of the two main discharge processes like ionization and gas rarefaction in DC-HiPIMS are analyzed. When the pulse voltage is higher than 600 V, the gas rarefaction effect becomes apparent. Overall, the ionization process is found to be dominant in the initial ∼100 μs during each pulse. The active species of Ar and Cr in DC-HiPIMS are higher than in HiPIMS unless that the pulse voltage reaches 900 V. However, the ionization degree in HiPIMS exceeds that in DC-HiPIMS at around 600 V. The electron temperature calculated by modified Boltzmann plot method based on corona model has a precipitous increase from 0.87 to 25.0 eV in HiPIMS, but varies mildly after the introduction of the superimposed DC current. Additionally, the current from plasma flowing to the substrate is improved when a DC current is superimposed with HiPIMS. [ABSTRACT FROM AUTHOR]