Amorphous Boron containing silicon carbo-nitrides created by ion sputtering

► Silicon SiBCN films were deposited by ion beam assisted deposition (IBAD) method. ► The films were amorphous, fully dense and showed high hardness up to 33 GPa. ► Low friction coefficient of about 0.3 may be the result of C nanoclusters. ► The material has an onset of rapid thermal oxidation at 1150 °C in air. ► The films have a Tauc bandgap between 2.2 and 2.8 eV and are insulating.