Influence of Y-doped induced defects on the optical and magnetic properties of ZnO nanorod arrays prepared by low-temperature hydrothermal process.

Chung-Yuan Kung,Teng-Tsai Lin,Lance Horng,Hone-Zern Chen,Chung-Jen Ou,Yu-Tai Shih,Chen-Cheng Lin,San-Lin Young,Ming-Cheng Kao

doi:10.1186/1556-276x-7-372

Abstract

One-dimensional pure zinc oxide (ZnO) and Y-doped ZnO nanorod arrays have been successfully fabricated on the silicon substrate for comparison by a simple hydrothermal process at the low temperature of 90°C. The Y-doped nanorods exhibit the same c-axis-oriented wurtzite hexagonal structure as pure ZnO nanorods. Based on the results of photoluminescence, an enhancement of defect-induced green-yellow visible emission is observed for the Y-doped ZnO nanorods. The decrease of E2(H) mode intensity and increase of E1(LO) mode intensity examined by the Raman spectrum also indicate the increase of defects for the Y-doped ZnO nanorods. As compared to pure ZnO nanorods, Y-doped ZnO nanorods show a remarked increase of saturation magnetization. The combination of visible photoluminescence and ferromagnetism measurement results indicates the increase of oxygen defects due to the Y doping which plays a crucial role in the optical and magnetic performances of the ZnO nanorods.

Highlights

The II-VI semiconductor zinc oxide (ZnO) with a direct wide bandgap (3.37 eV) and a large exciton binding energy (60 meV) has attracted substantial attention in the research community [1,2,3]
The reactions of the ZnO nanorod formation synthesized by acetates and HMTA can be summarized as the following chemical formulas [31]: ðCH2Þ6N4 þ 6H2O ! 6HCHO þ 4NH3
Substitution of Y for Zn during the growth of nanorods can be obtained, which is similar to the synthesized process of Ce-doped ZnO nanorods [32]

Summary

Introduction

The II-VI semiconductor zinc oxide (ZnO) with a direct wide bandgap (3.37 eV) and a large exciton binding energy (60 meV) has attracted substantial attention in the research community [1,2,3]. Progressive studies on the performance improvement of these one-dimensional nanostructured ZnOs for optoelectronic device applications have been performed by various growth methods, such as hydrothermal methods [8], vapor–liquid– solid [9], metal organic vapor-phase epitaxy [10], and pulsed laser deposition [11] and doped with impurities, Recently, the observation of ferromagnetism with high Curie temperature in III-V and II-VI semiconductors has attracted a great deal of attentions [22,23,24]. Non-magnetic elements, such Bi [29] or Li [30], have been doped into ZnO and room temperature ferromagnetism has been observed. Ferromagnetism would not originate from the non-magnetic dopants since they do not contribute to ferromagnetism

Methods

Results

Conclusion