Electronic properties of nanocrystalline LaNiO₃ and La _0.5Sr_0.5CoO₃ conductive films grown on silicon substrates determined by infrared to ultraviolet reflectance spectra

Electronic band structures of nanostructured LaNiO3 (LNO) and La0.5 Sr0.5 CoO3 (LSCO) films have been investigated by near-normal incident optical reflectance at room temperature. Dielectric constants of the conductive films in the photon energy range of 0.47-6.5 eV have been extracted with the Drude-Lorentz function. It is found that four interband electronic transitions can be uniquely assigned for the perovskite-type metallic oxides. Moreover, optical conductivity is approximately varied from 100 to 450 -1 cm-1 and shows a different variation trend for the LNO and LSCO layers. The discrepancy could be ascribed to diverse electronic structure, grain size, and crystalline formation.