Carbon ion self-sputtering attained by sublimation of hot graphite target and controlled by pulse injection of a neon-helium gas mixture

The operation of graphite targets with an increased temperature (HT - hot target) is studied for the case of gas injection magnetron sputtering (GIMS) of: 1) diamond-like carbon (DLC), and 2) carbon-silicon carbide (C-SiC) films. A purposely-thinned graphite target with a reduced thermal conductivity is applied for DLC deposition, extending its high temperature sputtering range up to 1636 degrees C. For the purpose of C-SiC synthesis four sockets with a silicon carbide powder are designed within graphite target. In this approach, the C-SiC target surface can be heated up to 1443 degrees C due to a greater energy input from impulse plasma, in the range 322-932 J. The HT sputtering is energy-controlled by a pulsed injection of a neon-helium gas mixture. High-energy Ne+ and He+ ions extend the length of pulsed GIMS discharge due to the self-sputtering effect observed during the deposition of DLC and C-SiC films. These conditions result in an almost 5-fold increase in the film growth rate (up to 185 nm/min) with respect to the operation with a cold target, which is due to the assisting vapour sublimation from custom-designed graphite-based targets. The temperature boosted HT GIMS discharge, proves to be an efficient tool for reaching relatively high (similar to 35 %) sp(3)-hybridized C content in both carbon-based materials. It also allows for tailoring the energy bandgap of DLC-based optical structure, in the range from 1.7 to 2.75 eV, due to the formation of the (C-C) and (C-O) bonds. Higher content of silicon oxide (SiO2-x) and silicon carbide (SiC) phases (15 - 23 %) in the case of C-SiC films results in hardness increase from 21.8 to 30.1 GPa.