Fabrication and wetting characteristics of copper thin film: An active layer for SPR-based sensor applications
Hossain, M. K., Aljishi, A., Khan, F., Ul-Hamid, A., & Rahman, M. M. (2025). Journal of Science: Advanced Materials and Devices, 10(1), 100839. https://doi.org/10.1016/j.jsamd.2024.100839
The goal of this study was to fabricate copper (Cu) thin films with optimized optical and wetting properties for use as active layers in surface plasmon resonance (SPR) sensors.
Key findings showed that Cu films, fabricated via DC sputtering and annealed at 200–600 °C, experienced significant changes in morphology, optical properties, and hydrophobicity. Annealing led to a red shift in absorption edges (from 464 to 616 nm), a decrease in energy band gaps (from 2.38 to 1.54 eV), and an increase in Urbach energy, indicating enhanced structural disorder. Wetting contact angle measurements revealed increased hydrophobicity at moderate annealing temperatures (200–400 °C), but a shift toward hydrophilicity at 600 °C due to surface roughening. Using Setfos (Fluxim AG), optical simulations determined that a 40 nm thick Cu film achieved optimal SPR performance, with SPR angles at 600, 700, and 800 nm wavelengths measured at 44.7°, 42.7°, and 42.15°, respectively.
Fluxim’s Setfos was instrumental in simulating and optimizing the spectral and angular reflectance characteristics of the Cu-based SPR sensor, enabling precise determination of optimal thickness and resonance conditions without extensive trial-and-error fabrication.
The findings are important because they establish copper as a promising, cost-effective alternative to gold and silver in SPR sensors, expanding material options for high-sensitivity biosensing and photonic applications.