Using Different Ions in the Hydrothermal Method to Enhance the Photoluminescence Properties of Synthesized ZnO-Based Nanowires

Ya-Fen Wei,Cheng-Fu Yang,Jei-Ru Shen,Wen-Yaw Chung,Chih-Cheng Chen

doi:10.3390/electronics8040446

Abstract

ZnO films with a thickness of ~200 nm were deposited on SiO2/Si substrates as the seed layer. Then Zn(NO3)2-6H2O and C6H12N4 containing different concentrations of Eu(NO3)2-6H2O or In(NO3)2-6H2O were used as precursors, and a hydrothermal process was used to synthesize pure ZnO as well as Eu-doped and In-doped ZnO nanowires at different synthesis temperatures. X-ray diffraction (XRD) was used to analyze the crystallization properties of the pure ZnO and the Eu-doped and In-doped ZnO nanowires, and field emission scanning electronic microscopy (FESEM) was used to analyze their surface morphologies. The important novelty in our approach is that the ZnO-based nanowires with different concentrations of Eu3+ and In3+ ions could be easily synthesized using a hydrothermal process. In addition, the effect of different concentrations of Eu3+ and In3+ ions on the physical and optical properties of ZnO-based nanowires was well investigated. FESEM observations found that the undoped ZnO nanowires could be grown at 100 °C. The third novelty is that we could synthesize the Eu-doped and In-doped ZnO nanowires at temperatures lower than 100 °C. The temperatures required to grow the Eu-doped and In-doped ZnO nanowires decreased with increasing concentrations of Eu3+ and In3+ ions. XRD patterns showed that with the addition of Eu3+ (In3+), the diffraction intensity of the (002) peak slightly increased with the concentration of Eu3+ (In3+) ions and reached a maximum at 3 (0.4) at%. We show that the concentrations of Eu3+ and In3+ ions have considerable effects on the synthesis temperatures and photoluminescence properties of Eu3+-doped and In3+-doped ZnO nanowires.

Highlights

Nanostructured semiconducting ZnO-based materials have been widely investigated, attracting significant attention due to their novel physical and chemical properties
We investigated the crystallinity of Eu3+ -doped ZnO nanowires synthesized with different concentrations of Eu3+ ions and synthesis temperatures using X-ray diffraction (XRD), and the results are shown in
ZnO-40-Eu, and 88 °C-grown ZnO-4-In nanowires, respectively. These results suggest that the additions of Eu3+ or In3+ affect the maximum intensities of the emission spectra, but they almost cannot affect wavelengths resulting in the maximum emission intensities

Summary

Introduction

Nanostructured semiconducting ZnO-based materials have been widely investigated, attracting significant attention due to their novel physical and chemical properties. Many different methods of growing ZnO-based nanostructured materials have been investigated. ZnO-based nanostructured materials, including nanotubes, nanowires (nanorods), and thin films, have been synthesized by various physical and chemical methods and used to fabricate sensors for a variety of applications. When all the synthesis methods are compared, using an aqueous solution to grow ZnO nanostructured materials is considered better, mainly due to low growth temperature and good potential for large-scale production. We could synthesize the Eu-doped and In-doped ZnO nanowires using the hydrothermal method at low temperature (below 100 ◦ C) and investigate the effects of different concentrations of Eu3+ and In3+ ions on their crystalline and photoluminescence properties. We show that the ions used and their concentrations have considerable effects on the synthesis temperatures and photoluminescence properties of ZnO-based nanowires

Experimental

XRD patterns the synthesized

Comparison of these

Conclusions