Film properties were estimated by using bulk optical constants derived from a Kramers-Kronig analysis of the bulk material. Films with thicknesses of 130-2000Å were prepared by sputtering and electron-beam evaporation onto substrates at between 100 and 1200C. The effective optical constants of the films were derived and were used, together with the modified Drude theory, to give the free-electron relaxation time. Conductivity measurements gave the electron mean free path. The optical and electrical film data were compared with the bulk properties of the material. The observed differences could be explained by the influence of crystal imperfections. The explanation was in qualitative agreement with information from X-ray diffractometer scans.

Diagnosis of the Optical Properties and Structure of Lanthanum Hexaboride Thin Films. Peschmann, K.R., Calow, J.T., Knauff, K.G.: Journal of Applied Physics, 1973, 44[5], 2252-6