High refractive index hydrogenated silicon carbide and process

A method for depositing a layer of amorphous hydrogenated silicon carbide (SiC:H), comprising

• a) introducing a gas mixture comprising a reactive gas and an inert gas into a reaction chamber of a plasma-enhanced chemical vapor deposition apparatus at a reactive gas to inert gas volume ratio of 1:12 to 2:3, wherein
• the reactive gas comprises a silicon source and a carbon source, and
• the inert gas comprises i) a first inert gas selected from the group consisting of helium, neon and mixtures thereof and ii) a second inert gas selected from the group consisting of argon, krypton, xenon and mixtures thereof, the inert gas having a volume ratio of first inert gas to second inert gas of 2:5 to 6:5;
• and
• b) reacting the reactive gas in the presence of a plasma;
• wherein
• the plasma is generated using plasma generation power at a frequency of from about 1-16 MHz at a power level of from 50 W to 300 W,
• the reactive gas and the inert gas are introduced at a total reactive gas flow rate of from 1000 sccm to 4000 sccm and a total inert gas flow rate of from 6000 sccm to 12,000 sccm, the total reactive gas flow rate and the total inert gas flow rate and the plasma conditions being sufficient to provide the amorphous hydrogenated silicon carbide layer having an atomic concentration ratio of Si of 50 at % to 60 at %, C of 3 at % to 13 at %, and H of 32 at % to 42 at % at a deposition rate of amorphous hydrogenated silicon carbide of from about 2 nm/sec to about 6 nm/sec, and
• the total reactive gas flow rate and the total inert gas flow rate and plasma conditions being such that the amorphous hydrogenated silicon carbide layer as deposited exhibits both a refractive index of not less than 2.6 and an optical loss of not more than 120 dB/cm at a wavelength of 825 nm.