An Ab-initio Study of Metallic and Semiconducting [001] SiC Nanowires(Condensed matter: electronic structure and electrical, magnetic, and optical properties)

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A detailed comprehensive ab-initio study of the structural, electronic and optical properties of the unpassivated and H-passivated SiC nanowires (NWs) grown along [001] direction having diameters lying in the range, 3.35 to 15.42Å has been made by employing the first-principles pseudopotential method within density functional theory (DFT) in the generalized gradient approximation (GGA). We investigate two types of the NWs having hexagonal and triangular cross-sections. The binding energy (BE) increases with the diameter of the NW because of decrease in the relative number of the unsaturated surface bonds. The band gap decreases with the diameter of the NW because of the quantum confinement. After atomic relaxation, appreciable distortion occurs in the NWs where the chains of Si- and C-atoms are curved in different directions. These distortions are reduced with the diameters of the NWs. The different NWs reveal different electronic properties, e.g., one NW is seen to be metallic whereas the other one is semi-metallic and the remaining NWs are semiconducting. The optical absorption is quite strong in the ultraviolet (UV) region but is quite appreciable in the visible and infrared (IR) regions. Thus, the NWs may have applications in the development of the devices emitting right from IR to UV electromagnetic radiations.
社団法人日本物理学会の論文
2009-03-15