The basic optical properties, optical constants and optical conductivity of bismuth single thin films and bismuth-copper bilayer systems

Several optical properties of thin bismuth films of 100, 150, 200, 250, and 350 Angstrom thicknesses and thin bismuth-copper bilayer systems, each of which is composed of the previous Bi films as an underlayer and a thin copper coating of 50 Angstrom thickness as a top layer, were measured and calculated. The measurements that included the reflectivity, transmissivity, and absorptivity in the visible region were carried out by the near normal incidence method, and the optical constants n and kappa were calculated by Welter's approximate expressions. The proper values of the optical constants were verified and confirmed by the characteristic matrix technique (CMT). All studied samples were deposited on glass substrates and prepared in a vacuum of 10(-4) Pa. The optical properties also included the calculation of the optical conductivity of these specimens. Analysis of the present results in comparison with published data and findings showed satisfactory consistency and agreement.