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

L A Udachan,N H Ayachit,Shiva L Udachan

doi:10.11144/javeriana.iyu23-2.isep

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.

Highlights

Thin chromium films have found many applications, for example, chromium was the first metal to be investigated as a thin film resistor material and has been used in photo-masks, integrated circuits, optical beam splitters, semi-reflective coatings and magnetic recording disks
The atomic force microscopy (AFM) observations indicate that the Cr grains of different sizes are formed at the beginning of film formation and scattered on the surface of the substrate
With a further increase in film thickness, the island structure is modified to become a semicontinuous structure with clear boundaries

Summary

Introduction

Thin chromium films have found many applications, for example, chromium was the first metal to be investigated as a thin film resistor material and has been used in photo-masks, integrated circuits, optical beam splitters, semi-reflective coatings and magnetic recording disks. The deposition parameters, include substrate temperature [1]–[4], substrate materials [5]– [7], deposition pressure, deposition rate [8], and application of DC fields [9] during the formation of the film, play vital roles in the nucleation, growth and other characteristics of films. The goal of the present work is to investigate the impact of substrate material on the microstructure, electron mean free path, specularity parameter, scattering power of the grain boundary, grain boundary reflection coefficient and resistivity of infinitely thick chromium films because of their smooth surface and dielectric nature. The microstructures of the chromium films were investigated via AFM & SEM images. Initial EDS analysis usually involves the generation of an X-ray spectrum from the entire scan area of the material under investigation; the material was identified as chromium

Methods

Results

Conclusion