Properties of diamond-like carbon films prepared by high power pulsed sputtering with two facing targets

Diamond-like carbon films are prepared by high power pulsed sputtering with a configuration of two facing targets. The discharge is called Penning discharge. Peak value of instantaneous power which is consumed in the plasma confined in a compact space reaches more than 10 kW in spite of an average power of 36-38 W. Growth rate is around 0.16-0.2 μm per hour in the pressure range from 0.5 to 2 Pa. In the Raman spectra, two very broad overlapping bands extending between 1200 and 1700 cm− 1 are assigned as the D (disorder) and G (graphite) bands. Both the intensity ratio of D band to G band and the G peak position do not strongly depend on the pressure at the pressure less than 1 Pa, beyond which the G peak position somewhat shifts to higher wavenumber and the intensity ratio increases. Meanwhile, the full width at half maximum of the G peak monotonically decreases with increasing pressure. In XPS C1s core level spectra, the rate of sp3 C bond related area is about 43-44% at the pressure lower than 1 Pa, beyond which the rate gradually decreases to about 38% with increasing pressure up to 2 Pa. The pressure dependence on the rate of sp3 C bond is reasonably consistent with the analysis of the Raman parameters. The hardness of films exceeds 25 GPa at the pressure less than 1 Pa, whereas the films with a moderate hardness of about 16.5 GPa are prepared at the pressure higher than 1 Pa.