共查询到18条相似文献,搜索用时 78 毫秒
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黑磷烯(black phosphorene, BP)因其"褶皱"的晶格结构而具有较高的比表面积,在气体吸附及气体传感器方面应用具有很大的优势.掺杂及缺陷对其传感性有较大的影响.本文以基于密度泛函理论的第一性原理方法为基础探究了本征、Al掺杂、含P原子空缺以及P空位与Al掺杂共存的黑磷烯体系吸附甲醛前后的传感行为.通过建立含缺陷和掺杂吸附体系的结构模型,计算得出了吸附能、能带结构及电荷转移等电子结构参数.结果表明,本征BP烯以及含P原子空缺的BP烯体系对甲醛分子吸附能力较弱, P原子空缺对电导率以及电荷转移没有影响,所以本征黑磷烯不适合用于传感器材料. Al掺杂和P空位与Al掺杂共存的BP烯体系,吸附甲醛分子的能力明显比前两种情况增强,电荷转移明显增加,改变了载流子浓度,提高了电导率.此外,在能带图中明显看到产生一个杂质能级,有效带隙明显变窄,表明Al掺杂提高了纯净和含P空位黑磷烯的传感性.因此, Al掺杂和P空位与Al掺杂共存的BP烯体系预计可成为一种新的传感器材料. 相似文献
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为了解释Ca掺杂与Mg掺杂在影响锂离子二次电池正极材料LiCoO2体系电子输运性质方面的不同效应,采用基于密度泛函理论的第一性原理方法研究了该体系的电子结构.计算结果表明,虽然在LiCoO2体系中用Ca或Mg替代Co都会在费米能级附近产生部分占据的受主带,但两者对应的电子态都具有明显的局域化特征;此外,与Mg掺杂体系明显不同的是,Ca掺杂体系的受主带与价带之间存在清晰的带隙.这一带隙的存在正是Ca掺杂不能明显提高LiCoO2体系电导率的主要原因.此外,Ca2+与Mg2+离子半径的较大差别也是造成这两个掺杂体系的电导率存在明显差异的一个重要因素. 相似文献
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利用第一性原理与半经典玻尔兹曼方程,计算并分析β型锑烯的声子色散、声子群速度、声子弛豫时间、晶格热导率及不同温度下的塞贝克系数、电导率和电子热导率随化学势的变化;结果表明:β型锑烯由于非平面六角结构,三支声学声子在Γ点附近均呈线性变化;声学声子对整个晶格热导率的贡献高达96.68%,而光学声子仅仅占到3.32%;由于较大的声光带隙(a-o gap)导致LA支在声子群速度和弛豫时间中占据主导地位,从而增大了LA支声子对整个热导的贡献;热电优值随温度的升高而增大,在费米面附近其绝对值最大可达0.275. 相似文献
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采用基于密度泛函理论的第一性原理方法研究了单层及多层黑磷晶体的能隙随层数和外加应力的变化.计算结果表明,体系能隙随着层数的增加而减小,当层数增加到10时,二维黑磷的能隙非常接近于其体材料值.层间的相互作用导致的能带劈裂是能隙减小的直接原因.应力对10层黑磷电子结构的影响也被研究.计算表明,压缩应力可以使10层黑磷从半导体转变为金属,而拉伸应力仅对能隙大小产生影响. 相似文献
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琚伟伟 《原子与分子物理学报》2016,33(6)
采用基于密度泛函理论的第一性原理方法研究了单层及多层黑磷晶体的能隙随层数和外加应力的变化.计算结果表明,体系能隙随着层数的增加而减小,当层数增加到10时,二维黑磷的能隙非常接近于其体材料值.层间的相互作用导致的能带劈裂是能隙减小的直接原因.应力对10层黑磷电子结构的影响也被研究.计算表明,压缩应力可以使10层黑磷从半导体转变为金属,而拉伸应力仅对能隙大小产生影响. 相似文献
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我们采用第一性原理方法研究了由单个和两个B80分子构成的分子结的电子输运性质。研究发现,单个B80分子是一个很好的导体,平衡电导为2.28G0(G0为电导量子,2e^2/h ),而由两个B80分子构成的二聚体则是一个绝缘体,电导仅为0.062G0。进一步的研究发现,二聚体的导电性可以通过电子掺杂来显著提高,如通过在每一个B80分子中用C替换一个B,电导可以提高到0.26G0。 相似文献
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锯齿型和扶手椅型六角形石墨烯分别跨接在两Au电极上, 构成分子纳器件, 同时考虑对六角形石墨烯分别进行B, N和BN局部规则掺杂. 利用第一性原理方法, 系统地研究了这些器件的电子输运特性. 计算结果表明: B及BN掺杂到扶手椅型六角形石墨烯, 对其电流有较好的调控效应, 同时发现本征及掺杂后的锯齿型六角形石墨烯均表现为半导体性质, 且N及BN掺杂时, 表现出明显的负微分电阻现象, 特别是N掺杂的情况, 能呈现显著的负微分电阻效应, 这也许对于发展分子开关有重要应用. 通过其透射特性及掺杂诱发的六角形石墨烯电子结构的变化, 对这些结果的内在原因进行了说明. 相似文献
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基于密度泛函理论的第一性原理计算,我们系统的研究了锗烯在Pt(111)、Au(111)和Al(111)表面的几何和电子结构.在这三种金属衬底上寻找到了9种结构,其中Al(111)-a、Au(111)-b和Pt(111)-c结构就是目前实验上已经成功制备的结构.我们还发现了其余6种目前理论和实验均没有提出,此外,Al(111)-b、Au(111)-a和Pt(111)-b结构的Dirac态仍保留,这些结构的形成能均大于范德瓦尔斯作用,因此非常有希望在实验上制备出来,应用于量子自旋霍尔效应的研究.本文的研究为锗烯在半导体衬底上的制备及应用奠定了理论基础. 相似文献
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The thermal transport properties of black and blue phosphorene nanoribbons and in-plane heterostructures are systematically investigated by non-equilibrium Green's-function method. Both edge shape and width have a sensitive influence on the thermal conductance of pristine black and blue phosphorene nanoribbons and they all exhibit a clear anisotropic thermal performance. Interestingly, the in-plane heterostructures possess a tunable thermal conductance which depends on the percentage of black phosphorene nanoribbons and the way how they are linked. These findings will provide new applications in nanoelectronic and thermoelectric devices based on phosphorene. 相似文献
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《Physics letters. A》2020,384(5):126123
Two-dimensional (2D) material of few-layer black phosphorus (BP) has recently attracted extensive interest owing to its tunable band gap and high carrier mobility. We investigate the electronic transport properties of zigzag black phosphorene nanoribbons (ZBPNRs) with asymmetric H, Li, O and Co edge saturations by employing the density functional theory in combination with the non-equilibrium Green's function. The computational results forecast that different types of saturated atoms at both edge of ribbons mainly contribute to the electronic transport properties of molecular junctions. The metal edge saturation of Co atom is used to the one edge of ZBPNR which can induce an identical electronic transport property. Interestingly, the negative differential resistance (NDR) phenomena can be observed in our proposed ZBPNR junctions with an analysis of internal physical mechanism. Our theoretical results could support the possibility of potential applications to design 2D electronic devices based on the material of BP in future. 相似文献
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Somayeh Fotoohi 《Physics letters. A》2019,383(4):369-375
By using first-principles calculations based on density functional theory and non-equilibrium Green's function, we present the electronic transport properties of two kinds of devices based on armchair phosphorene nanoribbons, namely, A device, and B device. In A device, the phosphorus atoms in the center of armchair phosphorene nanoribbon have been replaced by impurity atoms of the S and Si, whereas in the B device, the impurity atoms are at the edge of ribbon. The results show that the current–voltage characteristics for both devices have striking nonlinear features and the rectifying behaviors strongly depend on the positions of impurity atoms. The highest rectification ratio is obtained about 125992 at 0.8 V bias for B device. Moreover, only for A device, robust negative differential resistance is observed with a high peak–valley ratio 27500 in the bias range . The mechanism of the rectification behavior is analyzed in terms of the evolution of energy levels of the related electrodes and transmission spectra as well as the projected self-consistent Hamiltonian eigenvalues with the applied bias voltage. The results indicate that the asymmetric doping of the impurity atoms can lead to a robust rectification which can be utilized to design phosphorene-base rectifier with good performance. 相似文献
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《Physics letters. A》2020,384(35):126853
Regulating the magnetic state of 2D materials is becoming increasingly important for the next generation of spintronic devices. In this study, the first-principles calculation method is used to study the synergistic modulating effect of biaxial strain and vacancy defects on the magnetic properties of blue phosphorene. Results show that only Single Vacancy (SV) doping magnetizes the intrinsic blue phosphorene, Double Vacancy-1 (DV-1), Double Vacancy-2 (DV-2) and Double Vacancy-3 (DV-3) doped blue phosphorene are magnetized under biaxial strain. The magnetic states of SV, DV-1, DV-2 and DV-3 systems change with the intensity of biaxial strain. In some cases, the magnetic moment of the system can be changed from 0 μB to 4 μB. The biaxial strain affects the partially bonding structure near the defects, changes the position of the dangling bond, and thereby adjusts the magnetic state. Our research provides positive guidance for the future application of blue phosphorene in the semiconductor field. 相似文献
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Defect engineering on the electronic and transport properties of one-dimensional armchair phosphorene nanoribbons
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We investigate the electronic and transport properties of one-dimensional armchair phosphorene nanoribbons(APNRs) containing atomic vacancies with different distributions and concentrations using ab initio density functional calculations. It is found that the atomic vacancies are easier to form and detain at the edge region rather than a random distribution through analyzing formation energy and diffusion barrier. The highly local defect states are generated at the vicinity of the Fermi level, and emerge a deep-to-shallow transformation as the width increases after introducing vacancies in APNRs.Moreover, the electrical transport of APNRs with vacancies is enhanced compared to that of the perfect counterparts. Our results provide a theoretical guidance for the further research and applications of PNRs through defect engineering. 相似文献
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We investigate the electronic properties of metallic (7,7) carbon nanotubes (CNT) in the presence of a variety of tetra- and hexa-vacancy defects, by using the first principles density functional theory (DFT) combined with the non-equilibrium Green’s function technique. From the view point of energetic stability large vacancies tend to split into pentagon and heptagon (5-7) defects. However, this does not preclude the presence of “holes” in the carbon nanotube by the nanoelectronic lithography technique. We show that the states linked to large vacancies hybridize with the extended states of the nanotubes to modify their band structure. As a consequence, the hole-like defects in the CNT lead to more prominent electronic transport compared to the situation in the defective CNT consisting of pentagon-heptagon pair defects. Our study suggests the possibility to improve the electronic properties of a defective carbon nanotube via morphological modifications induced by irradiation techniques. 相似文献
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First principles calculations have been performed to investigate the electronic structures and transport properties of defective graphene nanoribbons (GNRs) in the presence of pentagon-octagon-pentagon (5-8-5) defects. Electronic band structure results reveal that 5-8-5 defects in the defective zigzag graphene nanoribbon (ZGNR) is unfavorable for electronic transport. However, such defects in the defective armchair graphene nanoribbon (AGNR) give rise to smaller band gap than that in the pristine AGNR, and eventually results in semiconductor to metal-like transition. The distinct roles of 5-8-5 defects in two kinds of edged-GNR are attributed to the different coupling between π? and π subbands influenced by the defects. Our findings indicate the possibility of a new route to improve the electronic transport properties of graphene nanoribbons via tailoring the atomic structures by ion irradiation. 相似文献
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《Physics letters. A》2020,384(24):126575
Inspired by MoS2-OH bilayer framework (Zhu et al. 2019 [19]), first principles calculations are applied to explore its possible configurations as well as their electronic and transport properties. The calculated results indicate O-MoS2 and OH…O-MoS2 are two primary configuration in MoS2-OH bilayer. It shows negligible difference in electronic structure between O-MoS2 and pure MoS2, but a flat band arise at the Fermi level in OH…O-MoS2. Their contact characteristics show larger binding energy with selected metals and smaller contact barrier with Pt electrode. Besides, the currents of both O-MoS2 and OH…O-MoS2 are enlarged compared with that of pure MoS2 in finite bias, indicating MoS2-OH bilayer may be potential candidate for future electron device applications. 相似文献