Electronic transport properties of an (8,0) carbon/boron nitride nanotube heterojunction

The structure of a heterojunction made up of an (8, 0) carbon nanotube and an (8, 0) boron nitride nanotube is achieved through geometry optimization implemented in the CASTEP package. Based on the optimized geometry, the model of the heterojunction is established. Its transport properties are investigated by combining the nonequilibrium Green's function with density functional theory. Results show that both the lowest unoccupied molecular orbital and the highest occupied molecular orbital mainly locate on the carbon nanotube section. In the current--voltage characteristic of the heterojunction, a rectification feature is revealed.     

Structural feature and electronic property of an (8, 0) carbon--silicon carbide nanotube heterojunction

A supercell of a nanotube heterojunction formed by an (8, 0) carbon nanotube (CNT) and an (8, 0) silicon carbide nanotube (SiCNT) is established, in which 96 C atoms and 32 Si atoms are included. The geometry optimization and the electronic property of the heterojunction are implemented through the first-principles calculation based on the density functional theory (DFT). The results indicate that the structural rearrangement takes place mainly on the interface and the energy gap of the heterojunction is 0.31eV, which is narrower than those of the isolated CNT and the isolated SiCNT. By using the average bond energy method, the valence band offset and the conduction band offset are obtained as 0.71 and --0.03eV, respectively.     

Electronic Transport Properties of （7,0） Semiconducting Carbon Nanotube

Electronic transport properties of a finite （7,0） carbon nanotube （CNT） coupled to Au （111） surfaces are investigated with a fully nonequilibrium Green＇s functions method combined with the density functional theory. The results show that the coupling effect between the CNT and Au electrode plays an important role in the transport properties, which leads to the formation of a high plateau in the transmission spectrum around Fermi energy. In addition, the current-voltage characteristic of the （7,0） CNT coupled to Au electrodes is different from an isolated （7,0） CNT.     

含反位缺陷碳化硅纳米管的电子结构和光学性质

基于第一性原理计算,对含有SiC反位缺陷或CSi反位缺陷碳化硅纳米管的电子结构和光学性质进行了研究.SiC缺陷在纳米管的表面形成了凸起,CSi缺陷在纳米管的表面形成了凹陷;这两种缺陷都导致在纳米管的导带底附近形成了缺陷能级,使得纳米管表现出n型电导;导带顶到杂质能级间的跃迁使得纳米管的光学带隙呈现了减小的趋势.这些结果对碳化硅纳米管电子器件和光学器件的研究都有较重要的参考价值.     

掺氮碳化硅纳米管电子结构的第一性原理研究

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. 关键词： 碳化硅纳米管 掺氮 第一性原理 电子结构     

反位缺陷对碳化硅纳米管电子结构和光学性质影响研究

采用基于密度泛函理论的第一性原理计算对含有反位缺陷（5,5）单壁碳化硅纳米管的电子结构和光学性质进行了研究.纳米管进行结构优化的结果显示,C_Si缺陷在纳米管表面形成了凹陷,Si_C缺陷形成了凸起;反位缺陷在纳米管的导带底附近形成了缺陷能级,使纳米管表现出n型导电的特点,由价带顶到缺陷能级的跃迁,在垂直和平行于纳米管管轴方向上形成了新的介电峰.     

p型K:ZnO导电机理的第一性原理研究

基于密度泛函理论,利用局域密度近似的第一性原理平面波赝势方法,对掺K以及含有氢填隙(H_i)、氧空位(V_O)、锌填隙(Zn_i)和锌空位(V_Zn)的K:ZnO电子结构分别进行了研究.结果表明,1) 单独掺K可引入浅受主,但系统总能增高;2) K与H共掺可降低系统总能,提升稳定性;3) V_O在K+H:ZnO中的形成比Zn_i困难得多,二者都是 关键词： 氧化锌 p型 第一性原理 电子结构