For infrared (IR) energy conversion applications stable and low-loss plasmonic materials are advantageous. Traditional plasmonic materials (i.e. Au and Ag) have been heavily utilized owing to their excellent plasmonic response in the UV-Vis region. Beyond these conventional metals, compound materials such as transparent conductive oxides, nitrides, or borides can have plasmonic properties in the IR. From the boride compounds, lanthanum hexaboride (LaB6) is attractive for its high conductivity, chemical stability, high melting point and more. This makes it a superb choice in IR plasmonics for thermal emitters. Here, using electron beam evaporation, high-quality epitaxial thin films of LaB6(001) were achieved on Si(001). The dielectric function exhibits a low-loss nature and good figure-of-merit from near IR region, making them promising for IR plasmonics. We fabricated spectrally selective optical cavity structures with narrowband thermal emission at operation temperatures above 1200°C.
