AUTHORS:

Win K., Martychowiec A., Sezemsky P., Seweryn A., Wróbel P., Sawczak M., Wolska A., Klepka M., Kulikowski K., Koba M., Śmietana M.

ABSTRACT:

Nitrogen-doped diamond-like carbon (N-DLC) thin films exhibit highly tunable electronic and optical characteristics, rendering them promising candidates for advanced optoelectronic applications. In this study, N-DLC coatings were deposited from a graphite target using both conventional direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS). For the HiPIMS process, pulse frequencies were systematically varied between 500 and 2000 Hz, while the nitrogen reactive gas fraction () was adjusted over the full range from 0 to 100%. Detailed structural, electrical, and optical analyses revealed that HiPIMS deposition yields films with an enhanced sp³ bonding fraction, which manifests as increased electrical resistivity and a reduced refractive index relative to DCMS films. An increase in frequency was induced to facilitate graphitization, leading to a concomitant rise in electrical conductivity and optical constants. Notably, the influence of nitrogen incorporation was distinctly non-monotonic: an optimal nitrogen concentration of yielded films with the highest electrical conductivity and refractive index. These findings underscore the intricate coupling between ion-energy-driven growth mechanisms and reactive gas chemistry, demonstrating that careful modulation of HiPIMS frequency and nitrogen concentration enables synergistic and precise tailoring of the optoelectronic properties of N-DLC thin films.

Diamond and Related Materials, 2026, vol. 166, art. 113775, doi: 10.1016/j.diamond.2026.113775