Structural and magnetic properties of Co-doped ZnO thin films grown by ultrasonic spray pyrolysis method. (April 2017)

• Record Type: Journal Article
• Authors: Baghdad, R.; Lemée, N.; Lamura, G.; Zeinert, A.; Hadj-Zoubir, N.; Bousmaha, M.; Bezzerrouk, M.A.; Bouyanfif, H.; Allouche, B.; Zellama, K.
• Is Part Of: Superlattices and microstructures. Volume 104(2017)
• Page Start: 553
• Page End: 569
• Publication Date: 2017-04
• Subjects: Cobalt doped ZnO -- Nanostructured thin films -- Ultrasonic spray pyrolysis -- ZnO bond length -- Bond force constant -- Raman spectroscopy -- Magnetic properties; Superlattices as materials -- Periodicals; Microstructure -- Periodicals; Semiconductors -- Periodicals; Superréseaux -- Périodiques; Microstructure (Physique) -- Périodiques; Semiconducteurs -- Périodiques; 621.38152
• DOI: 10.1016/j.spmi.2016.11.069
• Languages: English
• ISSNs: 0749-6036

Abstract

Abstract: Cobalt-doped ZnO thin films with several different percentage of Co from 0 up to 15 at% were synthesized via a cheap, simple and versatile method i.e. ultrasonic spray pyrolysis at atmospheric pressure and a substrate temperature of 350 °C. The structure of the as-prepared samples was characterized by X-ray diffraction (XRD), Raman spectroscopy and FTIR. The Co-doping effect is revealed by the presence of three additional peaks around 235, 470 and 538 cm −1 respect to the Raman spectra of the unsubstituted film. Fourier transform infrared spectroscopy (FTIR) put in evidence the decrease of the bond force constant f with increasing Co-doping. By ultra-violet visible near infrared (UV–Vis–NIR) spectroscopy on Co-doped samples it was possible to show the presence of additional absorption bands at approximately 570, 620 and 660 nm suggesting that Co 2+ ions do not change their oxidation when substituted to zinc and the ZnO lattice does not change its wurtzite structure as well. Finally, all our samples exhibit a paramagnetic behavior without any trace of intrinsic room temperature ferromagnetism. Highlights: The bond length ZnO ( L ) in the unit cell diminishes with increasing the rate of doping of the cobalt. FTIR results show the decreasing of the bond force constant f with increasing Cobalt doping. All our samples exhibit paramagnetic behavior because of the 3d electron of Co 2+ . The observed paramagnetism might also originate from oxygen vacancies and/or by zinc-related defects in the ZnO lattice.