Computational and experimental approach for investigation of epsilon-near-zero response in nitrogenated TiO2. (June 2022)

• Record Type: Journal Article
• Authors: Shahbaz, Hafsa; Saleem, Murtaza; Anwar, Muhammad Sabieh
• Is Part Of: Materials today communications. Volume 31(2022)
• Publication Date: 2022-06
• Subjects: Titanium oxynitride -- Thin films -- Ab-initio calculations -- Electronic properties -- Epsilon-Near-Zero; Materials science -- Periodicals; 620.11
• DOI: 10.1016/j.mtcomm.2022.103324
• Languages: English
• ISSNs: 2352-4928

Abstract

Abstract: This study presents simulation and experimental investigations on electronic and optical properties of titanium oxynitride. The computational studies were performed using the full potential-linearized augmented plane wave method (FP-LAPW) based on density-functional-theory (DFT) with the generalized gradient approximation on WIEN2k software. From the DFT simulations, electronic and optical properties such as band structure, density of states, refraction, extinction coefficient, absorption coefficient, epsilon, optical conductivity and reflectivity were extracted. Furthermore, titanium oxynitride thin films were fabricated using reactive magnetron sputtering. The films were grown using bottom-up approach under varying pressure ratios of oxygen and nitrogen gases working in the background vacuum. Various parameters such as thin films thickness and substrate temperature were changed with the target of achieving near-zero-epsilon behavior. X-ray diffraction and scanning electron microscopy were carried out to investigate the crystallinity, phases, and surface morphology of these films. Spectroscopic ellipsometry was employed to extract the various optical parameters specifically the epsilon-near-zero response of the thin films. This phenomenon is attributed to the mixture of phases. The composition dependence of the parameters observed in the grown films is in close agreement with what is predicted by the ab-initio calculations. Graphical Abstract: ga1 Highlights: DOS spectra reveal p-d hybridization in TiO2 . Band structure reduced with the increment of nitrogen concentration. Simulation results predicts ENZ response in TiO2−x Nx structures. Crystallinity of thin films undergoes a steady change with nitrogen content. The composite phases of TiO2, TiN, and TiOx Ny were observed in thin films.