Effect of silicon and oxygen dopants on the stability of hydrogenated amorphous carbon under harsh environmental conditions

A silicon- and oxygen-containing hydrogenated amorphous carbon (a-C:H:Si:O) coating was exposed to the harsh conditions of the low Earth orbit (LEO) environment (hyperthermal atomic oxygen, thermal cycling, ultraviolet radiation) aboard the International Space Station. X-ray photoelectron spectroscopy measurements indicated degradation of the near-surface region of a-C:H:Si:O through breakage and subsequent oxidation of carbon-carbon bonds as well as formation of a silica layer (shift of the silicon 2p signal to higher binding energies).349