Hydrogenated Amorphous Carbon Coatings for Calibration Targets of Fluorescence-Based Optical Instruments

Hydrogenated amorphous carbon (a-C:H) coatings are developed for calibration targets in fluorescence-based optical instruments. Fluorescence microscopy, integral to biological imaging and DNA sequencing, necessitates precise calibration using stable and reproducible photoluminescent structures. Traditional calibration materials, such as fluorescein dyes and fluorescent glass, pose challenges in terms of stability, integration, and uniformity. This study introduces a-C:H as a promising alternative. By employing reactive High Power Impulse Magnetron Sputtering (HiPIMS) coupled with plasma-enhanced chemical vapor deposition using toluene as a precursor, a-C:H coatings with varying amounts of hydrogen are synthesized. The incorporation of hydrogen, confirmed through Rutherford backscattering and elastic recoil detection analysis (RBS-ERDA), significantly enhances photoluminescence. By adjusting the HiPIMS parameters and toluene flow, the film's hydrogen content can be optimized to achieve intense and stable photoluminescence under laser excitation. Additionally, the stability of the coatings under repeated laser irradiation is significantly improved compared to traditional materials, with further enhancement achieved through multilayer structures incorporating aluminum nitride for thermal management. Overall, the results demonstrate that a-C:H coatings offer a robust and reliable solution for calibration targets in advanced fluorescence microscopy, such as next-generation DNA sequencing.