Comparison of Aluminum Nitride Nanowire Growth with and without Catalysts via Chemical Vapor Deposition
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Comparison of Aluminum Nitride Nanowire Growth with and without Catalysts via Chemical Vapor Deposition Kasif Teker1 and Joseph A. Oxenham1 1 Department of Physics and Engineering, Frostburg State University, 101 Braddock Road, Frostburg, MD 21532, U.S.A.
ABSTRACT This paper presents a systematic investigation of AlN nanowire synthesis by chemical vapor deposition using Al and NH3 on SiO2/Si substrate and direct nitridation of mixture of Al-Al2O3 by NH3. A wide variety of catalyst materials, in both discrete nanoparticle and thin film forms, have been used (Co, Au, Ni, and Fe). The growth runs have been carried out at temperatures between 800 and 1100oC mainly under H2 as carrier gas. It was found that the most efficient catalyst in terms of nanowire formation yield was 20-nm Ni film. The AlN nanowire diameters are about 20-30 nm, about the same thickness as the Ni-film. Further studies of direct nitridation of mixture of Al-Al2O3 by NH3 have resulted in high density one-dimensional nanostructure networks at 1100oC. It was observed that catalyst-free nanostructures resulted from the direct nitridation were significantly longer than that with catalysts. The analysis of the grown nanowires has been carried out by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and x-ray diffraction. INTRODUCTION Aluminum nitride (AlN) is a very important semiconductor material for electronic and optoelectronic applications. As a wide band gap (6.2 eV) III-V semiconductor, AlN has attracted great interest due to its inherent superior properties such as excellent thermal conductivity, low thermal expansion coefficient, high chemical stability, high electrical resistivity, and low electron affinity [1-3]. One-dimensional aluminum nitride (AlN) nanostructures are important not only for understanding fundamental concepts underlying the observed electronic, optical, and mechanical properties of materials, but also for potential applications in several fields including power transistors, heat sinks, surface acoustic wave filters, resonators, sensors, and piezoelectric nanogenerators. Thus, significant research has been devoted to the synthesis of 1-D AlN nanostructures with various fabrication methods. These fabrication methods include metal organic vapor deposition (MOCVD) [4], arc discharging process [5], chloride-assisted growth [6], carbothermal reduction [7], gas reduction nitridation [8], and CVD [9-15]. In addition, group III-nitride nanostructures attract interest due to their significant piezoelectric effect, which provides great potential for the integration of nanoelectronics and piezoelectricity [16]. This paper presents a systematic investigation of 1-D AlN nanostructure synthesis by chemical vapor deposition using Al and NH3 on SiO2/Si substrate and direct nitridation of mixture of Al-Al2O3 by NH3 as source materials. A wide variety of catalyst materials, in both discrete nanoparticle and thin film forms, have been used (Co, Au, Ni, and Fe). Furthermore, we have conducted tests about ca
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