Compositional control of plasma enhanced chemical vapor deposited diamond-like carbon/SiO2 nanocomposite thin films

Using the common alkoxy silane, tetraethoxysilane (TEOS), diamond-like carbon/SiO2 nanocomposite thin films were deposited at room temperature using a plasma enhanced chemical vapor deposition process. Compositional control could be obtained by adding oxygen to the TEOS/Ar RF plasma and also by varying the RF power. The index of refraction could be varied from 1.563 to 1.492 (at 634.1 nm) by adding 0 to 200 sccm of O-2 (at 0.18 W/cm(2) RF); and the addition of O-2 increased the optical clarity of the nanocomposite in the visible spectrum until it was completely transparent. However, this addition decreased the deposition rate substantially and shifted the carbon-bonding structure to graphitic carbon from diamond-like carbon, yet still remained hard enough to pass an elementary scratch test. TEOS presents itself as a versatile single-source precursor with the ability to deposit tunable dielectrics depending on flow chemistry or RF power.