Effects of process parameters on optical characteristics of diamond-like carbon thin films deposited using high-power impulse magnetron sputtering

Highlights: • Two operating modes for HiPIMS were used: Bipolar and Unipolar. • Non‑hydrogenated DLC films are transparent in visible light range. • The best transmittance of 86% for the DLC can be obtained in unipolar mode. • UV reflection of DLC film is increased to 20%. -- Abstract: High-power impulse magnetron sputtering (HiPIMS) is a physical vapor deposition technique, developed specifically for the low-temperature deposition of functional thin films. In this study, a graphite target was used for the deposition of diamond-like carbon (DLC) thin films of high optical transmittance on a quartz glass substrate at 25 °C – 30 °C using HiPIMS in unipolar and bipolar modes. Experiments were conducted to determine the influence of DC input power, deposition time, and bias voltage with a fixed duty cycle on the optical characteristics of the resulting amorphous DLC thin films. During deposition, the current-voltage characteristics of discharge with a graphite target were recorded. The optical characteristics were assessed using a UV/visible light-absorption detector and the structure of the DLC thin films was confirmed by Raman spectroscopy. DLC thin films produced in unipolar mode with deposition time of 1 min presented the highest best transmittance of 86%.