Non-destructive characterization of In/Ag and In/Cu diffusive layers

Microstructural, optical and electronic properties of In/Ag and In/Cu multilayers obtained by sequential evaporating of metals in a vacuum were investigated by using X-ray diffractometry, scanning electron microscopy and spectroscopic ellipsometry. Thicknesses of individual films were adjusted to atomic concentration ratios In:Ag(Cu) = 1:2. Creation of AgIn, Ag2In, AgIn2, CuIn, CuIn2(or CuIn2-x) and Cu2In intermetallic compounds was detected at room temperature. A stronger tendency to grow island-like films was observed for In/Cu system. The effective complex dielectric functions (<(epsilon) over tilde (E)> = <(epsilon) over tilde (1)(E)> + i <(epsilon) over tilde (2)(E)>) of In/Ag and In/Cu composite layers were evaluated from ellipsometric data in the photon energy range 1.14-5.0 eV. The free-carrier parameters and optical resistivity were determined using a semiclassical Drude-Lorentz model of the dielectric function. There was noticed a significant dependence of the optical resistivity on sample composition and surface morphology: rho(op) values ranged from 41 mu Omega cm to 145 mu Omega cm for In/Ag structures and from 20 mu Omega cm to 155 mu Omega cm for In/Cu multilayers. (C) 2009 Elsevier Ireland Ltd. All rights reserved.