Impact of substrates on the electrical properties of thin chromium films [Online First]

Abstract

Objective: We studied the impact of substrates on the electrical properties of thin chromium films. Substrates may serve many purposes, such as to define orientation, to conduct electrical current in vertical devices, as a gate in transistors, etc. The thickness range of the chromium films grown on both substrates was (3.5-70) nm. Methods and materials: We used Fuchs-Sondheimer(FS) and Mayadas-Shatzkes(MS) theories to analyze electrical resistivity data for chromium(Cr) films grown on both substrates simultaneously by thermal evaporation in vacuum, under identical deposition conditions. Results and discussion: The infinitely thick film resistivity (ρ0), conduction electron mean free path(l), specularity parameter(p), scattering power of the grain boundary(α') and grain boundary reflection coefficient(R') were found to depend upon the nature of the substrate and the binding force between them and evaporated chromium atoms. The growth and microstructure of the chromium films were examined using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Conclusions: Our experimental data exactly fits with the MS theory in the entire thickness range grown for the chromium films deposited on both the substrates. Examination of film structure by SEM indicated that the films consist of grains of relatively pure chromium of different sizes, and depends upon deposition conditions and parameters, which are important factors that dictate the structural properties of the films.

Examination of Film Thickness Dependence on Acoustic Impedance of Gold and Chromium Thin Films by Scanning Acoustic Microscopy

“…Particularly, mechanical characterization is fundamental for thin films designed for devices in which they may be subjected to stresses and damaged. X-ray diffraction (XRD) technique [1,2] can determine the crystallographic structure of a material, while scanning electron microscopy (SEM) [2] and atomic force microscopy (AFM) or atomic force acoustic microscopy (AFAM) [3,4] obtain two-dimensional structural information in nanometer scale. An alternative imaging modality called scanning acoustic microscopy (SAM) can be used for thin film surface characterizations [5][6][7].…”

“…Thin films are used in many applications such as optoelectronic and photovoltaic systems [8,9], magnetic storage systems [10] or chemical biosensors [11]. Their electrical or magnetic properties change according to their preparation conditions [12], thickness of the films [5], substrates on which they are grown [3] and also aging [13]. Chromium (Cr), being the first metal investigated as a thin film resistor with no superconductivity even under pressure, and gold (Au), being a unique material with high chemical stability and electrical conductivity especially in porous form [14], gain attention from scientists and therefore, highly examined.…”