Set of Techniques for High-Q Noble Metals Deposition: from Continous Ultrathin to Single-crystalline Films

Losses are the most serious challenges, which impede high-Q plasmonic devices rapid development. There are numerous types of plasmonic devices with conflicting requirements for the films. One can conclude that most devices require continuous silver and gold films with ultra-low losses, extremely low roughness, single-crystalline structure and maximum possible surface plasmon polarition wave (SPP) propagation length on various substrates including amorphous.
We present a full row of techniques as contribution to material platform. Among them single-crystalline ultra low loss (SCULL) sub-50 nm single-crystalline silver films, which provide SPP propagation length 200 μm (at wavelength 780 nm) [1] and allow ultra-bright single photon sources fabrication [2]. For amorphous substrates, we proposed polycrystalline big grain film deposition with high aspect ratios between grain size and film thickness that ensured high-Q light source fabrication [3]. Finally, for ultrathin films, less than 15 nm thick, we developed technologies to reduce percolation threshold of gold and silver without using wetting layers.
References
1. A. Baburin et. al. Opt. Mater. Express Vol. 8, Issue 11, (2018)
2. S. Bogdanov et al. Nano Lett., 18.8, (2018)
3. P. Melentiev et. al. Appl. Phys. Lett. 111, 213104, (2017)