掺氮碳化硅纳米管电子结构的第一性原理研究

First-principles study of the electonic structure of nitrogen-doped silicon carbide nanotubes

采用基于密度泛函理论的第一性原理计算,对本征碳化硅纳米管和掺氮碳化硅纳米管的电子结构进行了计算.计算表明本征(8,0)碳化硅为直接带隙半导体,能带间隙为0.94 eV;掺氮浓度为1.56%和3.12%的碳化硅纳米管的能带间隙减小为0.83 eV和0.74 eV.从差分电荷密度可以看出,能带间隙的减小是氮硅键与碳硅键相比共价成键能力降低的结果.

The electronic structures of the intrinsic and nitrogen-doped silicon carbide nanotubes （SiCNTs） have been calculated by first-principles approach based on the density functional theory. The intrinsic （8, 0） SiCNT is a direct band-gap semiconductor with a gap value of 0.94 eV. The band-gap of the SiCNT with the doping concentration of nitrogen being 1.56% and 3.12% is narrowed to 0.83 eV and 0.74 eV, respectively. The narrowing of the band-gap is the result of the weakening of the Si-N bonds compared with the corresponding Si-C bonds, which can be seen by comparing the charge density difference of the intrinsic SiCNT with that of the nitrogen-doped nanotube.