Bi-doping improves the magnetic properties of zinc oxide nanowires

Kazmi, Jamal and Ooi, Poh Choon and Goh, Boon Tong and Lee, Min Kai and Wee, M. F. Mohd Razip and Karim, Siti Shafura A. and Raza, Syed Raza Ali and Mohamed, Mohd Ambri (2020) Bi-doping improves the magnetic properties of zinc oxide nanowires. RSC Advances, 10 (39). pp. 23297-23311. ISSN 2046-2069, DOI

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Room-temperature ferromagnetism in the large and direct bandgap diluted magnetic semiconductor zinc oxide (ZnO) is attributed to the intrinsic defects and p-orbital-p-orbital (p-p) coupling interaction. However, due to oxidation, the ferromagnetism induced by defects is unstable. In the present work, the solution process synthesis route was utilized to grow pristine and bismuth-doped, highly crystalline ZnO nanowire (ZnO NW)-based samples. The FE-SEM images showed that the grown ZnO NWs have a preferred orientation along thec-axis in the (001) direction due to the anisotropic crystal nature of ZnO. X-ray photoelectron spectroscopy (XPS) confirmed the presence of Bi, and at a higher doping content, the bismuth oxide phase appeared. The XRD patterns showed the wurtzite crystal structure, and the large intensity of the (002) peak suggests that most of the reflection was from the top hexagonal face of the NWs, and thus, the wires are predominantly aligned along the c-axis. The TEM analysis further confirmed the crystal growth direction along the (001) direction. The UV-Visible absorption and PL measurements also showed a decrease in the bandgap with an increase in doping concentration, which may be associated with the sp-d exchange interaction between the localized d-electrons and band electrons of the Bi ions. Bi-doping tended to increase the PL intensity in the visible region. The magnetic properties measured by SQUID at 4 and 300 K showed ferromagnetic behaviour for both the pristine and Bi-doped samples. However, the saturation magnetization for the Bi-doped samples was higher compared to that of the pristine ZnO samples until the threshold doping value. The obtained results demonstrated that Bi-doping can be used to tune both the optical and magnetic properties of ZnO NWs, hence paving the way for future spintronics and spin-polarized optoelectronics applications.

Item Type: Article
Uncontrolled Keywords: Anisotropy; Bismuth compounds; Crystal orientation; Defects; Energy gap
Subjects: Q Science > Q Science (General)
Q Science > QC Physics
Divisions: Faculty of Science
Faculty of Science > Department of Physics
Depositing User: Ms Zaharah Ramly
Date Deposited: 01 Dec 2023 01:31
Last Modified: 01 Dec 2023 01:31

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