Preparation of silicon carbide nano-particles using a pulsed laser deposition method
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Preparation of silicon carbide nano-particles using a pulsed laser deposition method H. Kawasaki, Y. Suda, T. Ohshima, T. Ueda and S. Nakashima Sasebo National College of Technology 1-1 Okishin, Sasebo, Nagasaki 857-1193, Japan ABSTRACT We have developed a new pulsed laser deposition technique using two Nd:YAG laser beams for the nucleation of silicon carbide (SiC) crystalline nano-particles and single crystalline SiC thin films. Transmission electron microscopy and atomic force microscopy observation suggest that several nanometer size SiC particles can be prepared by the new pulsed laser deposition (PLD) method using two Nd:YAG laser beams (1064nm and 532nm). X ray photoelectron spectroscopy measurements suggest that the silicon/carbon composition ratio of the prepared SiC thin films can be controlled by laser fluence and wavelength. INTRODUCTION Nano size crystalline particles, such as fullerene (C60), have attracted a great deal of attention in the industrial production and application. Recently, silicon (Si) and/or silicon carbide (SiC) nano-particles are also attracted great interest due to their small size, low power consumption, and unique functionality. Si nano-particles have been studied enthusiastically as single-electron devices, especially as a quantum dot transistor. As the Si and/or SiC nano-particles show visible blue light emission property, those nano-particles have been investigated as optical devices. These particles have been prepared using several methods, such as plasma CVD method, sputtering method etc. However, it is difficult to prepare stable and single crystalline Si and SiC nano-particles. On the other hand, pulsed laser deposition (PLD) method has become a widely used technique for the deposition of thin films during the past few years due to the advantages of a simple system setup, wide ranging deposition conditions, wider choice of materials and higher instantaneous deposition rates. Especially, it is well known that this method shows high reproducibility to prepare crystalline thin films. Because of those versatility, we have developed several kinds of functional thin films, and we also prepared SiC thin films using conventional PLD method [1-3]. Experimental results suggest that poly-crystalline SiC thin film can be prepared using conventional PLD method at the substrate temperatures of >800 ˚C. However, nano size crystalline particles can not be prepared. In this paper, we have developed a new PLD technique using two Nd:YAG laser beams named "dual laser PLD method". We prepared SiC crystalline nano-particles and single crystalline thin films by the new PLD method using pure silicon and pure carbon targets in methane (CH4) gas, and evaluated the crystalline structure, chemical states of Si and C in the lattice and surface morphology using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and transmission electron microscopy (TEM). In order to investigate the growth mechanism in the plasma plume, we also observed two dimensional i
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