Synthesis of transparent and hard SiOC(−H) thin films on polycarbonate substrates by PECVD method

► We synthesized transparent and hard SiOC(−H) films from a mixture of TrMS and O2. ► Hardness and transparency can be controlled by changing the mixture ratio. ► Transparency deteriorated and hardness increased as TrMS mix ratio increased. ► Increasing TrMS mix ratio led to increase in Si-CH3 and decrease in caged Si−O−Si. ► We obtained SiOC(−H) films as hard as 6.5 GPa with a transparency of ~ 100%.