Optical properties of low-temperature pulsed DC-sputter deposited (≤70°C) hydrogenated carbon are presented. Increasing hydrogen incorporation into the sputter deposited carbon significantly decreases infrared optical absorption due to a decrease in deep absorptive states associated with dangling bonds. Hydrogen flow is optimized (hydrogen flow 3 sccm), achieving the best compromise between increased infrared transmittance and hardness for durable coating performance. Optical, environmental, and durability performance of pulsed DC-sputtered carbon incorporated in multilayer (a-C:H/Ge) infrared antireflective coatings indicates suitability as a durable infrared optical coating for commonly used infrared substrates, including temperature sensitive chalcogenide glass.
Gibson, D., Song, S., Fleming, L., Ahmadzadeh, S., Chu, H. O., Sproules, S., Swindell, R., Zhang, X., Navabpour, P., Clark, C., & Bailey, M. (2020). Durable infrared optical coatings based on pulsed DC-sputtering of hydrogenated amorphous carbon (a-C:H). Applied Optics, 59(9), 2731-2738. https://doi.org/10.1364/AO.378266