Surface morphology and optical properties of copper nitride thin film synthesized by DC sputtering

Abstract

The purpose of this research is to study the surface morphology and optical properties of copper nitride thin films. Copper nitride thin films were deposited on corning glass substrates by using DC sputtering technique. Five samples were prepared with five different deposition time to obtain samples of different thicknesses. Ellipsometer was used to measure thickness and refractive index. The surface morphology images were obtained by using Atomic Force Microscopy (AFM). Both transmission spectra and photoluminescence spectrum were obtained from UV-Vis-NIR spectrophotometer and Photoluminescence spectrometer, respectively. The films obtained were yellow to reddish-brown depending on increasing deposition time. The thickness of the samples increased as the deposition time increased. Thicknesses of films, d obtained were in range of 1092.38 nm to 1331.03 nm. Refractive index decreased as deposition times increased. The Atomic Force Microscopy images showed that the films were a smooth morphology and were seen like pyramidal islands when deposition time increased. Transparency of copper nitride thin film was very low in the visible region, but it slowly increased in the infrared range. The absorption coefficient, a of copper nitride thin films increased with increasing of photon energy. The average optical band gap energy, Eg obtained in range of 1.56 eV to 2.06 eV. The best emission peak for maximum intensity was about 380 nm obtained in photoluminescence emission for all samples, which refer to ultra-violet light in visible light region of electromagnetic spectrum.