Effective-mass theory of collapsed carbon nanotubes

Nakanishi, Takeshi; Ando, Tsuneya

doi:10.1103/physrevb.91.155420

Cited by 11 publications

(3 citation statements)

References 117 publications

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“…The successful methods to alter the band structures of graphene-like 2D materials include controlling the thickness or the stacking geometry of 2D materials, [9][10][11] quantum confinement of charge carriers from 2D to 1D nanoribbons or nanotubes, [12][13][14][15][16] chemical doping, [17][18][19] strain, [20][21][22][23] and atomic modification. [24][25][26] First-principles calculations show that the band structure of monolayer CuSe has a gap above the Fermi level.…”

Section: Introductionmentioning

confidence: 99%

Band engineering of honeycomb monolayer CuSe via atomic modification*

Gao¹,

Zhang²,

Sun³

et al. 2021

Chinese Phys. B

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Two-dimensional monolayer copper selenide (CuSe) has been epitaxially grown and predicted to host the Dirac nodal line fermion (DNLF). However, the metallic state of monolayer CuSe inhibits the potential application of nanoelectronic devices in which a band gap is needed to realize on/off properties. Here, we engineer the band structure of monolayer CuSe which is an analogue of a p-doped system via external atomic modification in an effort to realize the semiconducting state. We find that the H and Li modified monolayer CuSe shifts the energy band and opens an energy gap around the Fermi level. Interestingly, both the atomic and electronic structures of monolayer CuHSe and CuLiSe are very different. The H atoms bind on top of Se atoms of monolayer CuSe with Se-H polar covalent bonds, annihilating the DNLF band of monolayer CuSe dominated by Se orbitals. In contrast, Li atoms prefer to adsorb at the hexagonal center of CuSe, preserving the DNLF band of monolayer CuSe dominated by Se orbitals, but opening band gaps due to a slight buckling of the CuSe layer. The realization of metal-to-semiconductor transition from monolayer CuSe to CuXSe (X = H, Li) as revealed by first-principles calculations makes it possible to use CuSe in future electronic devices.

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Section: Introductionmentioning

confidence: 99%

Band engineering of honeycomb monolayer CuSe via atomic modification*

Gao¹,

Zhang²,

Sun³

et al. 2021

Chinese Phys. B

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“…2 层状材料典型地示出了不同的机械、电子和机械特性，光学和热传导特性，因此有望设计新型纳米器件，特别是下一代电子和光电子应用。尽管之前的研究主要集中在体相本来就是层状的二维原子晶体材料，如二硫化钼、黒磷等。随着材料合成技术的进步，也有少量的体相为非层状的二维材料被合成，如硒化铜 (CuSe) 。硒化铜是属于金属硫化物，其化合物广泛用于肖特基二极管、光学滤波器、超声波导体、光电探测器、气体传感器和热电转换器 [14] 。Buffiere 等 [15] 发现金属硫属化物半导体大多作为吸收层用于多晶薄膜太阳能电池中。Yang 等 [16] 使用 DFT 计算发现煤燃烧后的主要排放物 Hg0 可以被物理吸附在 CuSe(001)表面上的 Cu 顶部位置，形成 Hg-Cu 合金，当遇到表面活性配体(如硒单体)时，其转化为稳定的化学吸附硒化汞(HgSe) 。Masrat 等 [17] 发现过渡金属掺杂剂(Mn 和 Fe)对 CuSe 纳米结构的形态、磁性、光学和光催化行为有显著影响。过渡金属掺杂剂的加入导致材料的光催化活性，将降解率从 59.4%提高到 64.5%。可以用于废水处理和室温气体传感器。2020 年，Cheng 等 [18] 获得了一种新型的 CuSe/MoSe 2 2D/2D 面对面异质结光催化剂，它们在光催化降解和光电化学方面表现出优异的性能，展示出金属硒化物在环境处理和氢能中的应用前景。与体相本来就是层状的二维原子晶体材料相比，体相为非层状的二维材料晶体的相关研究报导较少 [19][20][21] 。本文研究的单层 CuSe 属于后者，是一种新的蜂窝状石墨烯类似物。单层 CuSe 由于本质上是具有金属性质的，不适合在电子器件中应用，所以要使 CuSe 在电子器件得到应用，需要改变单层 CuSe 的电子结构，让其具备半导体特性。改变类石墨烯二维材料的能带结构方法有很多，如化学掺杂 [22][23][24] 、应力变化 [25][26][27] 、控制二维材料的厚度 [28,29] 和原子修饰的方法 [30][31][32]…”

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First-principles study of surface modification of CuSe

Qiu-Yan¹,

Song²,

Jing³

et al. 2023

Acta Phys. Sin.

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Compared with the two-dimensional atomic crystal materials whose bulk phase is layered originally, the related research of two-dimensional material crystals whose bulk phase is non-layered is still very scarce. The monolayer CuSe studied in this paper belongs to the latter, which is a new honeycomb graphene analogue. Monolayer CuSe is not suitable for application in electronic devices because of its metallic nature. In order to find new two-dimensional atomic crystal materials with excellent performance suitable for application in electronic devices, in this paper, the change of CuSe from metal to semiconductor is realized by external atom modification. The first principle of density functional theory is used to study the energy band structure of monolayer CuSe after adding second periodic atoms at the top, center and bridge sites. The electronic structure of monolayer CuSe with Li and B atoms, including energy band structure, the density of states, differential charge density and crystal orbital Hamiltonian population analysis. The results show that after the addition of Li atom, the transition of CuSe from metallic to semiconductive can be realized at all three positions, and Li atom is more inclined to be modified at the hexagonal center of CuSe, with band gap of about 1.77eV, the Fermi level is biased towards the top of the valence band and exhibits a p-type semiconductor property, and is a direct bandgap semiconductor; Adding B atom at the top of Cu atom can also make CuSe semiconductive, with band gap of about 1.2eV, the conduction band minimum is at the K point, and the valence band maximum is at the Γ point. It belongs to an indirect band gap semiconductor, and the Fermi energy level is biased towards the conduction band minimum, exhibiting the characteristics of an n-type semiconductor. According to the results of differential charge density and crystal orbital Hamiltonian population, the B atom is bound to the top of the monolayer CuSe with the B-Se polar covalent bond. The first principle reveals the realization of metal-to-semiconductor transition from monolayer CuSe to CuXSe (X=Li, B), and the calculation results make it possible to use CuSe in future electronic devices.

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“…These deformations are predicted to be much stronger in CNTs partially covered by a metal contact, due to capillary forces [16]. While much efforts in exploring electronic structure in deformed nanotubes have been made [17][18][19][20] including effects of the external transverse electric field [21], little is known about how deformations produced by a metal modify the electronic structure and, as a result, the contact resistance.…”

mentioning

confidence: 99%

Band Structure and Contact Resistance of Carbon Nanotubes Deformed by a Metal Contact

Hafizi

Tersoff²,

Perebeinos

2017

Phys. Rev. Lett.

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Capillary and van der Waals forces cause nanotubes to deform or even collapse under metal contacts. Using ab initio band structure calculations, we find that these deformations reduce the band gap by as much as 30%, while fully collapsed nanotubes become metallic. Moreover, degeneracy lifting due to the broken axial symmetry, and wave functions mismatch between the fully collapsed and the round portions of a CNT, lead to a 3 times higher contact resistance. The latter we demonstrate by contact resistance calculations within the tight-binding approach.

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Effective-mass theory of collapsed carbon nanotubes

Cited by 11 publications

References 117 publications

Band engineering of honeycomb monolayer CuSe via atomic modification*

Band engineering of honeycomb monolayer CuSe via atomic modification*

First-principles study of surface modification of CuSe

Band Structure and Contact Resistance of Carbon Nanotubes Deformed by a Metal Contact

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