Temperature threshold for localized surface plasmon resonance in glancing angle deposited ultra-thin silver films

• Published in: Journal of physics. Condensed matter Vol. 32; no. 39; pp. 395701 - 395708
• Main Authors: De, Rajnarayan, Haque, S Maidul, Sikdar, M K, Sahoo, P K, Som, Tapobrata, Rao, K Divakar
• Format: Journal Article
• Language: English
• Published: IOP Publishing 16.09.2020
• Subjects: GLAD; LSPR; silver; thin film
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/1361-648X/ab966d

Low thickness silver (Ag) coatings (thickness ∼25 nm) were fabricated by electron beam evaporation technique equipped with glancing angle deposition (GLAD, 86°) arrangement at varrying substrate heating temperatures (viz 30 °C, 75 °C, 125 °C and 150 °C). Although all the GLAD-Ag films prepared up to 125 °C temperature were found to be plasmonic in nature, the localized surface plasmon resonance (LSPR) band was more prominent at 125 °C and disappeared at 150 °C temperature. The dielectric contribution in the overall dispersion of sample structure was maximum for 125 °C with dominating metallic contribution observed for 150 °C. Detailed investigation of 125 °C deposited GLAD-Ag sample revealed sharpening of the LSPR band with reduction in film thickness. The ultra-thin coating (∼5 nm) was found to be purely dielectric in nature with the most prominent LSPR band among the others. Overall, the substrate heating temperature of 125 °C was found to be the threshold for fabricating plasmonic GLAD-Ag films with the best result observed for the ultra-thin (∼5 nm) specimen.