Conformal spray-deposited fluorine-doped tin oxide for mid- and long-wave infrared plasmonics

Abstract

Nanocrystalline spray-deposited fluorine-doped tin oxide (FTO) was investigated for mid- and long-wave infrared plasmonics. Silicon lamellar gratings were conformally coated with FTO, and the excitation of surface plasmon polaritons (SPP) was investigated via their angle and wavelength-dependent reflectivity. Photon-to-SPP coupling efficiency as a function of grating parameters, and in comparsion to gallium-doped zinc oxide (GZO) gratings, was quantitatively analyzed based on a figure of merit related to the sharpness and depth of the coupling resonance. Conformal spray-deposited FTO would be useful in mid- and long-wave infrared plasmonic channel wave guides.