Synthesis of GaN nanowires by Tb catalysis
Introduction
GaN is a promising candidate for the fabrication of optoelectronic devices and high temperature/power electronic devices due to its direct wide-band gap, large exciton binding energy, and breakdown voltage [1]. One-dimensional nanostructured materials of this kind have potential application in the field of full color panel display and high electron migration rate nanometer electronic devices [2]. In recent years, the synthesis, characterization, and application of GaN nanostructures have gained considerable attention, and some research groups have succeeded in synthesizing GaN nanostructures by various methods [3], [4], [5], [6], [7], [8], [9]. Among these methods, the metal catalyst-assisted growth is the most successful approach because it can offer simple and size-controllable growth of many semiconductor nanostructures. Rare earth metals catalysts La and Nd for nanostructures growth have been reported [10], [11]. So far as we know, the growth of GaN nanostructures employing rare earth metal as catalyst has been infrequently reported, Tb is one of rare earth elements and can be employed as catalyst material. According to our previous experimental results [12], [13], [14], the intermediate layer between Si substrate and Ga2O3 had effect on the morphology and characteristics of GaN nanostructures, therefore we attempted a novel route using Tb as the catalyst and synthesized unexpectedly radial GaN nanowires. In this work, as-grown GaN nanowires possess unique shape and show good characteristics, which indicate that Tb is a good catalyst. This growth method allows a continuous synthesis and produces high quality GaN nanowires at relatively high purity and low cost. Accordingly, it is probably used for commercial-scale production.
Section snippets
Experimental processes
Firstly, Si(1 1 1) substrates were washed with absolute ethyl alcohol, and then ultrasonic cleaned in acetone, absolute ethyl alcohol, and de-ionized water for 30 min in sequence. Secondly, Ga2O3/Tb thin films were deposited in turn on Si(1 1 1) substrates by sputtering a Tb target (99.95%) and a sintered Ga2O3 (99.99%) target in a JCK-500A radio frequency magnetron sputtering system. The sputtering chamber was evacuated by a turbomolecular pump to a background pressure of 1.8 × 10−3 Pa, and then argon
Results and discussions
The surface morphology of the samples is characterized by SEM. Fig. 1(a and b) show the typical SEM images at different magnifications, the light-yellow layer is composed of nanowires, and the nanowires can be observed clearly with about 50–100 nm in diameter and 10–20 μm in length. Furthermore, most of the nanowires are very tenuous and have smooth surface. Many nanowires come out of the same site of the substrate and take on radial structure, which indicate that Tb probably plays the role of
Conclusions
Radial GaN nanowires were synthesized successfully through magnetron sputtering and ammoniating technique. Rare earth metal Tb was employed as the catalyst of GaN nanowires growth. The structure, morphology, and composition of as-grown samples were studied by XRD, SEM, TEM, HRTEM, and FTIR. The results showed that the nanowires are pure hexagonal wurtzite single-crystal GaN with lengths for 10–20 μm and diameters for 50–100 nm, which is advantageous for the applications in nanodevices.
Acknowledgement
The work is supported by the Key Research Program of National Natural Science Foundation of China (Grant No. 90201025 and No. 90301002).
References (21)
- et al.
J. Cryst. Growth
(2000) - et al.
Chem. Phys. Lett.
(2000) - et al.
Chem. Phys. Lett.
(2006) - et al.
Solid State Commun.
(2007) - et al.
Mater. Lett.
(2007) - et al.
J. Cryst. Growth
(2006) - et al.
J. Cryst. Growth
(1998) - et al.
Nanostruct. Mater.
(1999) - et al.
J. Cryst. Growth
(2006) - et al.
J. Chem. Phys.
(2005)