Fabrication of zigzag and square spiral Cu nanostructures: Influence of substrate rotation on the structural, optical and electrical properties

Abstract

Copper (Cu) thin films were deposited by using glancing angle deposition in the form of zigzag and square spiral nanostructures. Thin films were fabricated under different azimuthal rotations (φ = 180°, 90°, 45°, 22.5° and 11°), to the thickness of approximately 300 nm. Morphological, chemical and structural properties were investigated by field-emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. For the optical characterization of the samples spectroscopic ellipsometry was used, while the electrical properties were analyzed by four-point probe method. It was found that as the azimuthal rotation decreases, deposited nanostructures become more porous with larger number of grown arms. Both, optical and electrical analyses revealed that the properties of the obtained thin films are significantly influenced by growth mechanism. By decreasing the φ parameter, the surface plasmon resonance peak was shifted from 1038.9 nm to 1676.6 nm, which can be correlated with the porosity of Cu structures. Besides, it was found that the optical and electrical properties of the thin films are also strongly dependent on the concentration of defects.