Infrared laser deposition of high-quality CsBH4 epitaxial thin films stable under atmospheric conditions

Abstract We have demonstrated the growth of CsBH 4 (001) epitaxial thin films utilizing an IR laser deposition technique. The thin film exhibited coherent growth with a tensile strain from the substrate, resulting in its crystallinity superior to other kinds of metal borohydride thin films reported in earlier studies. Moreover, the notable chemical stability of CsBH 4 enabled surface morphological and optical characterizations even under atmospheric conditions. The optical transition energy values estimated from a Tauc plot were found smaller than the theoretical ones previously reported, and DFT calculations suggested a partial deficiency of Cs + or [BH 4 ] − created in the thin films.