Growth of SiC Thin Films on (100) and (111) Silicon by Pulsed Laser Deposition Combined with a Vacuum Annealing Process
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Abstract Crystalline 3C-SiC thin films were successfully grown on (100) and (111) Si substrates by using ArF pulsed laser ablation from a SiC ceramic target combined with a vacuum annealing process. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were employed to study the effect of annealing on the structure of thin films deposited at 800'C. It was demonstrated that vacuum annealing could transform the amorphous SiC films into crystalline phase and that the crystallinity was strongly dependent on the annealing temperature. For the samples deposited on (100) and (111) Si, the optimum annealing temperatures were 980 and 920'C, respectively. Scanning electron microscope (SEM) micrographs exhibited different characteristic microstructure for the (100) and (111) Si cases, similar to that observed for the carbonization layer initially formed in chemical vapor deposition of SiC films on Si. This also showed the presence of the epitaxial relationship of 3C-SiC[100]//Si[100] and 3CSiC[1 1 ]//Si[l 11] in the direction of growth.
1. Introduction Silicon carbide's excellent physical and electrical properties, such as wide band- gap, high thermal conductivity, high breakdown electric field, high saturated electron drift velocity and resistance to chemical attack, provides a promising material for high-temperature, high-power and high-frequency electronic devices [1-2], as well as optoelectronic devices [3-4]. Cubic SiC (3C-SiC) is attractive owing to high electron mobility and high saturation velocity. As a result, there is an increasing interest in the growth of high quality 3C-SiC heteroepitaxial films on silicon. Since Matsunami and coworkers pioneered the single crystalline growth of 3C-SiC films on Si(100) by chemical vapor deposition(CVD)[5], CVD has become the most frequently used method for growth of SiC thin films [6-9]. In a typical CVD process, reactants consisting of a mixture of Si1 4 and C 3 H 8 diluted in H2 are flowed over a silicon substrate heated to 1300'C or above, to achieve epitaxial growth of SiC films. However, this method suffers from high hydrogen content and crystalline lattice defects in SiC films as a result of the very high substrate
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temperatures. Although epitaxial 3C-SiC films on Si have been reported at 750'C lui, the development of other lower temperature methods is desirable. Recently it has been demonstrated that crystalline SiC films can be grown on Si substrates by pulsed laser deposition (PLD), a novel and powerful thin film growth technique at relatively low temperature. Rimai [11,12], Balloch [13], and Capano [14] have all reported preparation of 3C-SiC films on silicon. However, the former employed temperatures of 1000'C or higher, while the crystallinity of the SiC films reported by the latter two was poor. In this study, we report oriented SiC films on (100) and (111) Si substrates grown by pulsed laser deposition (PLD) at 800'C combined with a vacuum annealing process. The purpose
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