Optimizing the OpticalResponse of Uniaxial CeriumHexaboride Films for High-Temperature Plasmonic Applications

Refractory materials with good optical properties are required for the development of novel high-temperature photonic and plasmonic photothermal applications. Whereas conventional plasmonic materials have excellent optical properties but low melting points, most refractory metals exhibit low plasmonic responses and oxidize easily in the atmosphere. Hence, in this study, cerium hexaboride (CeB₆) thin films are grown via electron-beam deposition on Si(100) and sapphire substrates. Epitaxial growth of this material is achieved under specific conditions, thus yielding high crystallinity and strong plasmonic polarizability within the infrared spectral region. The optical properties of CeB₆ improved significantly depending on the template substrate and growth conditions, achieving a six times higher plasmonic figure-of-merit on R-sapphire compared with on Si substrates. The high performance of CeB₆ films, as reflected by their superior plasmonic figures-of-merit particularly in the near-infrared region (1.0–2.0 μm) compared with conventional refractory materials, renders them highly promising candidates for photothermal and optoelectronic applications.