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1.
The stability and electronic structure of hypothetical InN nanotubes were
studied by first-principles density functional theory. It was found that the
strain energies of InN nanotubes are smaller than those of carbon nanotubes
of the same radius. Single-wall zigzag InN nanotubes were found to be
semiconductors with a direct band gap while the armchair counterparts
have an indirect band gap. The band gaps of nanotubes decrease with
increasing diameter,
similar to the case of carbon nanotubes. 相似文献
2.
N. Zibouche A. Kuc T. Heine 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(1):49
MoS2 and WS2 layered transition-metal dichalcogenides are indirect
band gap semiconductors in their bulk forms. Thinned to a monolayer, they undergo a
transition and become direct band gap materials. Layered structures of that kind can be
folded to form nanotubes. We present here the electronic structure comparison between
bulk, monolayered and tubular forms of transition metal disulfides using first-principle
calculations. Our results show that armchair nanotubes remain indirect gap semiconductors,
similar to the bulk system, while the zigzag nanotubes, like monolayers, are direct gap
materials, what suggests interesting potential applications in optoelectronics. 相似文献
3.
Seifert G Terrones H Terrones M Jungnickel G Frauenheim T 《Physical review letters》2000,85(1):146-149
Structural and electronic properties as well as the stability of MoS2 nanotubes are studied using the density-functional-based tight-binding method. It is found that MoS2 zigzag ( n,0) nanotubes exhibit a narrow direct band gap and MoS2 armchair ( n,n) possess a nonzero moderate direct gap. Interestingly, the ( n,n) tubes show a small indirect gap similar to the direct gap of ( n,0) nanotubes. Simulated electron diffraction patterns confirm the existence of armchair and zigzag disulphide nanotubes. The structure of the MoS2 nanotube tips is explained by introducing topological defects which produce positive and negative curvature. 相似文献
4.
Within tight-binding model, the band gaps of armchair and zigzag carbon nanotubes (CNTs) under both uniaxial tensile and torsional strains have been studied. It is found that the changes in band gaps of CNTs depend strongly on the strain type. The torsional strain can induce a band gap for armchair CNTs, but it has little effect on band gap of the zigzag CNTs. While the tensile strain has great effect on band gap of zigzag CNTs, but it has no effect on that of the armchair CNTs. More importantly, when both the tensile and torsional strains are simultaneously applied to the CNTs, the band gap changes of armchair CNTs are not equal to a simple sum over those induced separately by uniaxial tensile and torsional strains. There exists a cooperative effect between two kinds of strains on band gap changes of armchair CNTs. But for zigzag CNTs, the cooperative effect was not found. Analytical expressions for the band gaps of armchair and zigzag CNTs under combined uniaxial–torsional strains have been derived, which agree well with the numerical results. 相似文献
5.
《Physics letters. A》2014,378(5-6):565-569
The band-gap modulation of zigzag and armchair graphane-like SiC nanoribbons (GSiCNs) under uniaxial elastic strain is investigated using the density functional theory. The results show that band gap of both structures all decreases when being compressed or tensed. In compression, both zigzag and armchair GSiCNs are semiconductors with a direct band gap. However, in tension, the armchair GSiCNs undergo a direct-to-indirect band-gap transition but the zigzag GSiCNs still have a direct band gap. These results are also proved by HSE06 method. This implies a potential application of the graphane-like SiC nanoribbons in the future pressure sensor and optical electronics nanodevices. 相似文献
6.
A new class of non-carbon nanotubes based on Group III and Group V elements (aluminum and phosphorus, respectively) is considered. The equilibrium geometry, energy characteristics, and electronic structure of the AlP nanotubes were calculated using the density functional theory. These calculations demonstrated that the AlP nanotubes are energetically stable structures. It was found that a low strain energy (approximately 0.01–0.07 eV) is required for rolling a two-dimensional hexagonal AlP structure into a tube. The AlP nanotubes are found to be wide-band-gap semiconductors with a band gap of 2.05–3.73 eV with direct (for the zigzag type) or indirect (for the armchair type) transitions between the top of the valence band and the bottom of the conduction band. The band gap of these nanotubes increases with the tube diameter, approaching the band gap of a two-dimensional hexagonal AlP layer. 相似文献
7.
We studied the electronic structure and optic absorption of phosphorene (monolayer of black phosphorus) under strain. Strain was found to be a powerful tool for the band structure engineering. The in-plane strain in armchair or zigzag direction changes the effective mass components along both directions, while the vertical strain only has significant effect on the effective mass in the armchair direction. The band gap is narrowed by compressive in-plane strain and tensile vertical strain. Under certain strain configurations, the gap is closed and the energy band evolves to the semi-Dirac type: the dispersion is linear in the armchair direction and is gapless quadratic in the zigzag direction. The band-edge optic absorption is completely polarized along the armchair direction, and the polarization rate is reduced when the photon energy increases. Strain not only changes the absorption edge (the smallest photon energy for electron transition), but also the absorption polarization. 相似文献
8.
O. S. Lebedeva N. G. Lebedev 《Russian Journal of Physical Chemistry B, Focus on Physics》2014,8(5):745-751
The results of a theoretical research into the band gap of strained doped carbon nanotubes of two structural modifications of the “armchair” and “zigzag” types are described. The electronic states in the doped nanotubes are considered in terms of the periodic Anderson model. Nitrogen and boron atoms are selected as donor and acceptor substitutional defects, respectively. The dependences of the band gap of the carbon nanotubes on impurity concentration and compressive and tensile strain are studied. 相似文献
9.
Structural and electronic properties of narrow single-walled GaN nanotubes with diameter from 0.30 to 0.55 nm are investigated using the density functional method with generalized-gradient approximation. The calculations of total energies predict that the most likely GaN nanotubes in our calculation are (2,2), (3,2) and (3,3) nanotubes. From a detailed analysis we find that these narrow single-walled GaN nanotubes are all semiconductors, of which the armchair and chiral tubes are indirect-band-gap semiconductors whereas the zigzag ones have a direct gap except for (4,0) tube. The indirect band gap of (4,0) tube can stem from band sequence change induced by curvature effect. Our results show that the π-π hybridization effect and the formation of benign buckling separations play a key role in the band sequence changes of (4,0) tube. 相似文献
10.
在紧束缚理论的基础上,推导出轴向拉伸和扭转形变时碳纳米管(CNT)的能带公式.结果显示拉伸和扭转形变都可以改变CNT的导电性质,在金属型和半导体型之间转变,特别是对于锯齿型CNT,根据n 与3的余数关系,在拉伸和扭转中分别显示出三种不同的变化规律.进一步应用场效应晶体管Natori理论模拟计算形变对CNT场效应晶体管的电流-电压特性的影响,锯齿型CNT根据n 与3的余数关系表现出不同的电流变化趋势,而对于扶手椅型CNT轴向拉伸不改变电流;在扭转形变时,CNT电流急剧升高,特别是扶手椅型CNT.锯齿型CNT和扶手椅型CNT的电流随扭转角度和外电压行为明显不同.在某些特定的扭转角度,电流随扭转角度变化非常显著,显示出锯齿型CNT和扶手椅型CNT发生半导体型与金属型之间的转变.
关键词:
碳纳米管
紧束缚理论
费米能级
能带结构 相似文献
11.
The structural, electronic, elastic, mechanical properties and stress-strain relationship of chair, boat, and stirrup conformers of fully hydrogenated h-BN(fh-BN) are investigated in this work using the Perdew-Burke-Ernzerhof(PBE) function in the frame of density functional theory. The achieved results for the lattice parameters and band gaps of three conformers in this research are in good accordance with other theoretical results. The band structures of three conformers show that the chair, boat, and stirrup are direct band gap with a band gaps of(3.12, 4.95, and4.95 e V), respectively. To regulate the band structures of fh-BN, we employ a hybrid functional of Heyd-ScuseriaErnzerhof(HSE06) calculations and the band gaps are 3.84(chair), 6.12(boat), and 6.18 e V(stirrup), respectively.The boat and stirrup fh-BN exhibits varying degrees of mechanical anisotropic properties with respect to the Young's modulus and Poisson's ratio, while the chair fh-BN exhibits the mechanical isotropic properties. Furthermore, tensile strains are applied in the armchair and zigzag directions related to tensile deformation of zigzag and armchair nanotubes,respectively. We find that the ultimate strains in zigzag and armchair deformations in stirrup conformer are 0.34 and0.25, respectively, larger than the strains of zigzag(0.29) and armchair(0.18) deformations in h-BN although h-BN can surstain a surface tension up to the maximum stresses higher than those of three conformers of fh-BN. Furthermore, the band gap energies in three conformers can be modulated effectively with the biaxial tensile strain. 相似文献
12.
运用紧束缚能带理论,研究拉伸形变下BC3纳米管的能带结构. 研究表明:随着拉伸和压缩强度的不断增加,BC3纳米管的导带能级和价带能级逐渐靠近,最终发生能带交叠. 压缩形变下能带的交叠程度可达05 eV,而拉伸形变下只有02 eV. 对于扶手椅型BC3纳米管,随着拉伸和压缩的不断增加,BC3纳米管首先由直接半导体转化为间接半导体,进而发生能带的交叠,表现出金属性. 在无形变时,扶手椅型BC3纳米
关键词:
3纳米管')" href="#">BC3纳米管
能隙
拉伸形变
半导体 相似文献
13.
In this work, we performed first principles calculations based on self-consistent charge density functional tight-binding to investigate different mechanisms of band gap tuning of silicene. We optimized structures of silicene sheet, functionalized silicene with H, CH3 and F groups and nanoribbons with the edge of zigzag and armchair. Then we calculated electronic properties of silicene, functionalized silicene under uniaxial elastic strain, silicene nanoribbons and silicene under external electrical fields. It is found that the bond length and buckling value for relaxed silicene is agreeable with experimental and other theoretical values. Our results show that the band gap opens by functionalization of silicene. Also, we found that the direct band gap at K point for silicene changed to the direct band gap at the gamma point. Also, the functionalized silicene band gap decrease with increasing of the strain. For all sizes of the zigzag silicene nanoribbons, the band gap is near zero, while an oscillating decay occurs for the band gap of the armchair nanoribbons with increasing the nanoribbons width. At finally, it can be seen that the external electric field can open the band gap of silicene. We found that by increasing the electric field magnitude the band gap increases. 相似文献
14.
本文基于密度泛函理论计算分析了手性参数为(17,0)、(20,0)、(26,0) (10,10)、(12,12)、(15,15)的碳化硅纳米管的能带图,态密度及主要光学性质。结果表明:锯齿型与扶手椅型碳化硅纳米管均具有明显的半导体性质;在相近直径下,扶手椅型碳化硅纳米管带隙宽度要大于锯齿型碳化硅纳米管的带隙宽度;碳化硅纳米管的光吸收峰在100nm~200nm之间,可用于制作紫外线探测器件。 相似文献
15.
Using the first-principles calculations, electronic properties for the F-terminated AlN nanoribbons with both zigzag and armchair
edges are studied. The results show that both the zigzag and armchair AlN nanoribbons are semiconducting and nonmagnetic,
and the indirect band gap of the zigzag AlN nanoribbons and the direct band gap of the armchair ones decrease monotonically
with increasing ribbon width. In contrast, the F-terminated AlN nanoribbons have narrower band gaps than those of the H-terminated
ones when the ribbons have the same bandwidth. The density-of-states (DOS) and local density-of-states (LDOS) analyses show
that the top of the valence band for the F-terminated ribbons is mainly contributed by N atoms, while at the side of the conduction
band, the total DOS is mainly contributed by Al atoms. The charge density contour analyses show that Al–F bond is ionic because
the electronegativity of F atom is much stronger for F atom than for Al atom, while N–F bond is covalent because of the combined
action of the stronger electronegativity and the smaller covalent radius. 相似文献
16.
Wen-Jay Lee Jee-Gong Chang Shin-Pon Ju Chia-Hung Lee 《Journal of nanoparticle research》2011,13(10):4749-4756
The deformation mechanism of zinc oxide (ZnO) nanotube has been first examined by molecular dynamics. The result demonstrated that ZnO nanotubes relax it excess strain via the phase transformation from an armchair structure to a fourfold-coordinated structure, then to a zigzag structure, which is started by a slip deformation. In contrast to carbon, silicon carbide, and boron nitride nanotubes, they relax it local stress via the transformation of the Stone?CWales transformation. After yielding, the 8-4 dislocation loops are found and the numbers of 8-4 dislocation loops grow up, which relax the tensile strain at the necking region and leads the work hardening. Finally, the nanotube is broken down by crack deformation at the interface between different phases. 相似文献
17.
18.
用第一性原理方法系统地研究硫化锌纳米管的稳定性、电子性质和掺杂磁性质.比较三种纳米管的稳定性.研究表明,六边形截面的双壁管的稳定性最高,相同截面的单壁管稳定性次之,而圆截面的之字形和扶手椅纳米管稳定性最低.电子能带结构计算表明它们都是直接带隙半导体.纳米管表面氢吸附后,六边形截面的单壁管转变为间接带隙半导体.研究了磁性原子掺杂六边形截面管的磁性质.发现掺杂纳米管的形成能比纯纳米管的形成能低,说明掺杂过程是一个放热反应.纳米管的总磁矩等于掺杂的磁性原子的磁矩.这些单掺杂纳米管在可调磁的新材料方面有潜在的应用价值. 相似文献
19.
M. Rezaei-Sameti 《Physica B: Condensed Matter》2012,407(18):3717-3721
The electrical properties and NMR parameters of the pristine and Ga-doped structures of two representative (8, 0) zigzag and (4, 4) armchair of boron phosphide nanotubes (BPNTs) have been investigated. The structural geometries of above nanotubes have been allowed to relax by optimization and then the isotropic and anisotropic chemical shielding parameters (CSI and CSA) of 11B and 31P have been calculated based on DFT theory. The results reveal that the influence of Ga-doping was more significant on the geometries of the zigzag model than the armchair one. The difference of band gap energies between the pristine and Ga-doped armchair BPNTs was larger than the zigzag model. Significant differences of NMR parameters of those nuclei directly contributed to the Ga-doping atoms have been observed. 相似文献
20.
Y. Zhang M. Han 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,76(2):277-282
Using the π orbital tight-binding model and the
multi-channel Laudauer-Büttiker formula, the combined effect of
Aharonov-Bohm effect (induced by an axial magnetic field) and uniaxial
strain on quantum conductance oscillations of the electronic Fabry-Perot
resonators composed of armchair and metallic zigzag single-walled carbon
nanotubes (SWNTs) has been studied. It is found that, for the case of the
armchair SWNT, conductance oscillations near the band gap are dominated by
Aharonov-Bohm effect, while the conductance oscillations in other regions
are dominated by the uniaxial strains. The combined effect of Aharonov-Bohm
effect and uniaxial strains on quantum conductance oscillations is not
obvious. But, for the case of the metallic zigzag SWNTs, obvious
single-channel transport and one or two conductance oscillations existing in
two different gate voltage ranges were found by the combined effect of
uniaxial strain and axial magnetic field. 相似文献