Influence of Ammoniating Temperatures on Microstructures, Morphologies and Optical Properties of GaN/Nb Nanostructures b
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Influence of Ammoniating Temperatures on Microstructures, Morphologies and Optical Properties of GaN/Nb Nanostructures by RF Magnetron Sputtering Technique Feng Shi*, Chengshan Xue College of Physics and Electronics, Shandong Normal University, Jinan, P.R.China, 250014
Abstract: GaN nanowires and nanorods have been successfully synthesized on Si (111) substrates by magnetron sputtering through ammoniating Ga2O3/Nb thin films and the effects of ammoniation temperatures on growth of GaN nanowires and nanorods were analyzed in detail. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and photoluminescence spectra were carried out to characterize microstructures, morphologies, and optical properties of GaN samples. The results demonstrate that sample after ammoniation at 950 ℃ is single crystal GaN with hexagonal wurtzite structure and high crystalline quality, having the size of 30 - 80 nm in diameter. After ammoniation at 1000 ℃, GaN nanorods appear with smooth and clean surface and more than 100 nm in diameter. The optical properties of GaN nanowires grown at 950 ℃ and nanorods grown at 1000 ℃ are best with strong emission intensities. Keywords: Nanostructures; Magnetron sputtering; Ammoniating temperature; 1. Introduction As an attractive wide band-gap (3.39 eV direct gap at room temperature) semiconductor material, the GaN nanostructures have attracted great attention for their innovative physics properties and potential applications in optoelectronic devices[1,2]. However, the growth of the GaN nanostructures with high quality is the basic pre-condition for the fabrication of GaN-based components. There are many methods for the fabrication of the GaN nanostructures to date [3-6]. Of these methods, the metal catalyst-assisted growth is of great significance in fabricating the GaN nanostructures. According to our previous experimental results, the intermediate layers between Si substrates and Ga2O3 had great influences on the morphologies and characteristics of the GaN nanostructures. Therefore, we attempted a novel route via Nb as the intermediate layer and synthesized unexpectedly large-scale GaN nanowires and nanorods by ammoniation radio frequency (RF) magnetron sputtering method. That is, Nb, one element of transition metal, is employed as catalyst material forming the intermediate layer between Si substrate and Ga2O3 film to growth one-dimensional GaN nanostructures. The microstructures, morphologies and photoluminescence (PL) optical properties were characterized and the effects of the ammoniation temperatures on the growth of the GaN nanostructures is studied in particular as a progress report of the results published previously in the other papers[7-11]. 2. Experimental procedure In our experiment, metal Nb and Ga2O3 were deposited on the polished n-type Si(111) substrates in turn employing a JCK-500A magnetron sputtering system.The *Corresponding author: Shi Feng, Tel & Fax: +86 531 86182521, Email:[email protected]
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