Synthesis of nano-diamond-like carbon for protective optical window coating applications

This study reports the fabrication of carbon using ions of carbon generated by high temperature, high density and extremely non-equilibrium argon plasma produced in modified dense plasma focus device. Carbon is deposited using two bursts of focussed plasma on n-type silicon substrates kept at a temperature of 20 (room temperature) and 130 degrees C. The formation of nano-diamond-like carbon (nano-DLC) is observed at substrate temperature of 130 degrees C. The samples deposited at different substrate temperatures are found to have amorphous in nature as observed from X-ray diffraction studies. These amorphous samples of carbon and nano-DLC possess nanostructures of average size similar to 27 and similar to 10 nm for 20 and 130 degrees C substrate temperature, respectively, as obtained from atomic force microscopy and scanning electron microscopy studies. The possibility of formation of nano-DLC was analysed using Raman measurements. Peaks related to D and G band of graphitic carbon are observed in Raman spectra of both the samples. However, the samples grown at substrate temperature of 130 degrees C show peaks related to nano-grain of diamond in Raman spectra, indicating high sp(3) content, thereby confirming the formation of nano-DLC. The hardness measurement reveals the maximum value of hardness similar to 45.5 GPa for nano-DLC sample, which reconfirms that sample is of nano-DLC nature. The nano-DLC are found to have band gap of similar to 2.45 eV, which makes the nano-DLC a potential candidate for applications in protective optical window coating.

Automated summary

This study demonstrates the fabrication of nano-diamond-like carbon using ions of carbon generated by high temperature, high density and non-equilibrium argon plasma. The nano-DLC samples deposited on silicon substrates at 130 degrees Celsius show the presence of nanostructures. The Raman measurements confirm the formation of nano-DLC with high sp(3) content and a band gap of approximately 2.45 eV.