Effect of Gd Doping on Optical and Magnetic
Properties of Vertically Aligned ZnO Nanorod Arrays
K.S.Ranjith1, P.Saravanan2, D.Mangalaraj3, R.T.Rajendrakumar1,3*
Advanced Materials and Devices, Department of Physics, Bharathiar University, Coimbatore, India
2
Defence Metallurgical Research Laboratory, Hyderabad - 500 058, Andhra Pradesh, India
3
Department of Nanoscience and Technology, Bharathiar University, Coimbatore, India.
*
Corresponding author’s e-mail: rtrkumar@buc.edu.in, Tel.: +91-9789757888
Abstract
We demonstrate the growth of one dimensional (1D)
vertically aligned Gd doped ZnO nanorods (NRs) with different
doping concentrations: 0, 2, 4, 6 and 8% synthesized by a simple
low temperature solution method. The structural, optical and
magnetic properties were studied at room temperature (RT).
Enhancement in the ferromagnetic (FM) properties in terms of
increase in saturation magnetization, Ms = 1.3 x10-2 emu/g to 4.2
x10-2 emu/g indicates the incorporation of Gd ions into
the ZnO lattice sites.
Keywords: Gd doped ZnO, Nanorods, Ferromagnetisum,
Introduction
Integration of diluted magnetic semiconductor
materials in the today’s electronics demand very low
dimensions, in order to utilize the advantages offered by
the spins. Currently, there is a tremendous interest in the
fabrication of 1-D semiconductor nanostructures owing to
its potential in electronic and optoelectronic devices [1].
ZnO doped with magnetic transition metals have attracted
much attention, as these materials hold the possibility of
DMS [2]. In addition, realization of spintronic devices from
the bottom up approach might be feasible by adopting the
DMS NRs. Accordingly, the present study is aimed in
preparing 1-D aligned Gd-doped ZnO nanostructures
through a simple method.
Experimental Methodology
ZnO buffer layer coated glass substrate was
immersed in a solution containing equal mole of zinc
nitrate hexahydrate and hexamine. . The growth solution
was maintained at 97 °C for 4 h and washed and dried at
250 C. For Gd doped ZnO NRs, molar ratio between the
zinc nitrate and europium nitrate was varied with the ratios
of 98:2, 96:4, 94:6 and 92:8 and the growth process was
followed as similar to ZnO NRs.
Results
The X-ray diffraction studies confirmed the
wurtzite phase for the Gd-doped ZnO NRs with intense
(002) peak and this peak shift towards lower angle with
increasing Gd concentrations. This indicates that the Gd
atoms were successfully incorporated into the ZnO lattices.
The synthesized NRs exhibited typical average diameter of
about ~80 nm and length of about 1.2 µm. From UV-Vis
spectra, a blue shift on band edge absorption and change in
band gap with Gd doping was observed. The
photoluminescence studies showed that the Gd doping
enhances the visible emission peak intensity through
increasing the defect states in the NRs. Both the undoped
and Gd-doped ZnO NR arrays show the RT-FM. Presence
of FM in the Gd-ZnO with increase in coercivity and
remanence on increasing the Gd doping concentration
reveal that Gd ions play a vital role in enhancing the
magnetic properties of ZnO NRs.
0.04
Magnetisation (emu/g)
1
Undoped ZnO NRs
6% Gd doped ZnO NRs
0.02
0.00
-0.02
-0.04
-15000
-10000
-5000
0
5000
10000
15000
Applied field (Oe)
Fig. 1 (a) SEM image vertically ZnO NR arrays, (b) M-H
cure of pure and Gd doped ZnO NRs.
Conclusion
In summary, 1-D vertically aligned Gd-doped
ZnO NR arrays were successfully synthesized by simple
low temperature solution growth. The Gd doped ZnO NRs
exhibit an obvious RTFM ordering, which is attributed
from the enhanced oxygen defect states.
References
[1] Z. F. Wu et al, Synthesis and magnetic properties of
Cu doped ZnO nanorods via radio frequency plasma
deposition. Appl. Phys. Lett, 93, (2008) 023103.
[2] Tong L. N et al, Effects of H2 annealing on
ferromagnetism of Ni-doped ZnO powders. Solid State
Commun, 150, (2010), 1112.