Effect of substrate temperature and radio frequency power on compositional, structural and optical properties of amorphous germanium carbide films deposited using sputtering

Fabrication of Ge_xC_{1 − x} has been a big challenge because of the solubility of C in Ge. Only a small percentage of Ge−C bonds (11.6%) have been introduced so far. In this work, a-Ge_xC_{1 − x} with GeC content up to 21% has been fabricated with 50 W RF power at 250 °C by reactive sputtering methods. The effects of the radio frequency power and substrate temperature on the yield of GeC were analysed in detail. The GeC percentage by volume was found to first increase and then decrease with increasing substrate temperature. Introduction of C into the Ge matrix seems to tune the optical bandgap over a range of 2.7 eV to 1.0 eV depending on the combination of substrate temperature and radio frequency power.