First-principles Study On The X (X=N, P, As, Sb) Doped(9.0) Single-walled SiC Nanotubes

Since the discovery of carbon nanotubes in1991, peculiar and varied properties of many kinds of nanutubes were researched by theory and experiments. Through this research it was discovered that the CNTs are metal or semiconductor depending on tubular diameter and chirality but the BNNTs, SiCNTs, GaNNTs and ZnONTs are viewed as always semiconductors independent of any factors. SiC is a kind of third generation of wide band-gap semiconductor material and has been widely utilized in the fields of high temperature, high voltage, high frequency and large power due to its wide band-gap, highly saturated electron mobility, high breakdown field strength, high heat conductivity and strong radiation resistance. SiC nanotubes were made by two kinds of IV elements which had larger electronegativity difference, with strong polar covalent bond, so the physical properties are very stable. It is proved by a large quantity of theoretical and experimental research that SiC nanotube of low-dimensional materials has stable lower states, and thus has more stable electronic, magnetic and chemical properties than those of carbon nanotube, which implies more extensive potential applications in the fields of aviation, microelectronics, photoelectronics and other special environments.IIIA and VA elements are often doped silicon or silicon carbide bulk material. Since the SiCNTs exhibit semiconducting behavior, IIIA and VA elements could be considered as n-type and p-type dopants respectively. Boron (B) and nitrogen (N) atoms are commonly present in the structures of SiC counterparts as impurities; therefore, investigations of the effects of these impurities on the properties of SiCNTs could be an important task. The B-doped and N-doped models of SiCNTs could be considered as p-type and n-type semiconductors, respectively, because the valence shell of B atom has fewer electrons and that of N atom has more electrons than both of Si and C atoms.Many scholars do a lot of research on the B/N-doped model’properties by the first-principles theory.Commonly used as a dopant in the semiconductor, nitrogen doped in SiC nanotubes was reported, but VA elements doped in SiC nanotubes have not been studied so far. In this work, we firstly investigate the properties of X(X=N, P, As, Sb) doped zigzag (9.0) SiC nanotubes by density functional theory (DFT) calculations, explain the peculiar electronic structures of Xsi and Xc, predict the X-Si and X-C bond style in (9.0) SiC nanotubes. These researches are obviously needed by the experimental progresses in building nanodevices based on SWSiCNTs. These result indicated that with the addition of atomic radius and reduction of electronegativity, dopant of VA elements will bring many changes of electronic properties. When one As or Sb replace one Si atom, the model shows the character of p-type semiconductor, it is so different from the character of semi-metallic in N doped model, n-type semiconductor in P doped model. The calculated results indicated not every VA elements dropped SiC nanotubes display the character of n-type semiconductor.