Ion dose dependence on solid phase epitaxy of amorphous silicon carbide induced by ion implantation
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Ion dose dependence on solid phase epitaxy of amorphous silicon carbide induced by ion implantation In-Tae Bae1, Manabu Ishimaru 2, Yoshihiko Hirotsu 2 1 2
Department of Materials Science and Engineering, Osaka University, Osaka, Japan The Institute of Scientific and Industrial Research, Osaka University, Osaka, Japan
ABSTRACT Amorphous silicon carbides (a-SiC) fabricated by Xe+ ion implantation into 6H-SiC (0001) to fluences of 1015 and 1016/cm2 have been annealed at 850 oC for 1 hour. Transmission electron microscopy (TEM) observations revealed that the 1015 Xe+/cm2 implanted sample was completely recrystallized, while most of the a-SiC remains in the 1016 Xe+/cm2 implanted sample. Pair-distribution function analyses of both of the as-implanted samples show that the peak intensity of Si-C heteronuclear bonds is higher and the peak intensities of Si-Si and C-C homonuclear bonds are lower in the 1015 Xe+/cm2 implanted sample, indicating that the atomistic structure of the 1015 Xe+/cm2 implanted sample is more chemically ordered than that of the 1016 Xe+/cm2 implanted sample. This result suggests that more chemically ordered atomistic structure of 1015 Xe+/cm2 implanted a-SiC leads to complete recrystallization during thermal annealing.
INTRODUCTION SiC is an important semiconductor material due to its application for electronic and optoelectronic devices. From the viewpoint of processing technology, it has been revealed that conventional diffusion-based techniques cannot be applied, since the diffusivity of impurities in SiC is very low below 1700 oC [1]. Ion implantation doping also has some problems. For instance, radiation damage in SiC is extremely stable and the damage accumulation during high dose implantation gives rise to amorphization of the material [2]. As an alternative method, solid phase epitaxy of ion-beam-induced a-SiC is an important technique. Generally, the threshold crystallization temperature of >1450 oC is required for solid phase epitaxial growth of ion-beam-induced a-SiC [3]. However, recent studies have shown that recrystallization of implantation-induced a-SiC already occurs at a temperature as low as ~800 oC [4]. This discrepancy is due to the lack of knowledge about recrystallization process in a-SiC. Particularly, no work has been performed to study the relationship between ion doses and threshold
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crystallization temperatures. In this study, we performed Xe+ implantation into bulk SiC with ion doses 10 times different each other (1015 and 1016/cm2) and annealed them at temperatures ranging from 800 to 900 oC.
EXPERIMENTAL PROCEDURES 6H-SiC [0001] substrates obtained from Cree Research were irradiated with 150 keV Xe+ ions at room temperature to fluences of 1015 and 1016/cm2 in the Ion Beam Materials Laboratory at Los Alamos National Laboratory. Thermal annealing was then performed at temperatures ranging from 800 to 900 oC for 1 hour using a vacuum furnace operating with ~3x10-5 Pa. TEM specimens were prepared by a combination of tripod polishing technique and ion t
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