The Experts below are selected from a list of 135 Experts worldwide ranked by ideXlab platform
Hao Zhang - One of the best experts on this subject based on the ideXlab platform.
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first principles study on the electronic optical and transport properties of monolayer α and β gese
Physical Review B, 2017Co-Authors: Hao Zhang, Hezhu Shao, Rongjun Zhang, Bo Peng, Yongyuan Zhu, Heyuan Zhu, C M SoukoulisAbstract:The extraordinary properties and the novel applications of black phosphorene induce the research interest on the monolayer group-IV monochalcogenides. Here using the first-principles calculations, we systematically investigate the electronic, transport and optical properties of monolayer $\alpha-$ and $\beta-$GeSe, the latter of which was recently experimentally realized. We found that, monolayer $\alpha-$GeSe is a Semiconductor with direct band gap of 1.6 eV, and $\beta-$GeSe displays Indirect Semiconductor with the gap of 2.47 eV, respectively. For monolayer $\beta-$GeSe, the electronic/hole transport is anisotropic with an extremely high electron mobility of 7.84 $\times10^4$$cm^2/V\cdot {s}$ along the zigzag direction, comparable to that of black phosphorene. Furthermore, for $\beta-$GeSe, robust band gaps nearly disregarding the applied tensile strain along the zigzag direction is observed. Both monolayer $\alpha-$ and $\beta-$GeSe exhibit anisotropic optical absorption in the visible spectrum.
Asadollah Bafekry - One of the best experts on this subject based on the ideXlab platform.
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introducing novel electronic and magnetic properties in c3n nanosheets by defect engineering and atom substitution
Physical Chemistry Chemical Physics, 2019Co-Authors: Asadollah Bafekry, Saber Farjami Shayesteh, F M PeetersAbstract:Using first-principles calculations the effect of topological defects, vacancies, Stone–Wales and anti-site and substitution of atoms, on the structure and electronic properties of monolayer C3N are investigated. Vacancy defects introduce localized states near the Fermi level and a local magnetic moment. While pristine C3N is an Indirect Semiconductor with a 0.4 eV band gap, with substitution of O, S and Si atoms for C, it remains a Semiconductor with a band gap in the range 0.25–0.75 eV, while it turns into a metal with H, Cl, B, P, Li, Na, K, Be and Mg substitution. With F substitution, it becomes a dilute-magnetic Semiconductor, while with Ca substitution it is a ferromagnetic-metal. When replacing the N host atom, C3N turns into: a metal (H, O, S, C, Si, P, Li and Be), ferromagnetic-metal (Mg), half-metal (Ca) and spin-glass Semiconductor (Na and K). Moreover, the effects of charging and strain on the electronic properties of Na atom substitution in C3N are investigated. We found that the magnetic moment decreases or increases depending on the type and size of strain (tensile or compression). Our study shows how the band gap and magnetism in monolayer C3N can be tuned by introducing defects and atom substitution. The so engineered C3N can be a good candidate for future low dimensional devices.
Tomasz J Ochalski - One of the best experts on this subject based on the ideXlab platform.
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direct and Indirect band gaps in ge under biaxial tensile strain investigated by photoluminescence and photoreflectance studies
Physical Review B, 2018Co-Authors: Dzianis Saladukha, Michael Clavel, Felipe Murphyarmando, Gabriel Greenediniz, Myrta Gruning, Mantu K Hudait, Tomasz J OchalskiAbstract:Germanium is an Indirect Semiconductor which attracts particular interest as an electronics and photonics material due to low Indirect-to-direct band separation. In this work we bend the bands of Ge by means of biaxial tensile strain in order to achieve a direct band gap. Strain is applied by growth of Ge on a lattice mismatched InGaAs buffer layer with variable In content. Band structure is studied by photoluminescence and photoreflectance, giving the Indirect and direct bands of the material. Obtained experimental energy band values are compared with a $\mathbf{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbf{p}$ simulation. Photoreflectance spectra are also simulated and compared with the experiment. The obtained results indicate direct band structure obtained for a Ge sample with $1.94%$ strain applied, with preferable $\mathrm{\ensuremath{\Gamma}}$ valley to heavy hole transition.
Yu Wang - One of the best experts on this subject based on the ideXlab platform.
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Benzene-like N6 rings in a Be2N6 monolayer: a stable 2D Semiconductor with high carrier mobility
Journal of Materials Chemistry C, 2017Co-Authors: Yu Wang, Zhifa Liu, Urs AeberhardAbstract:Designing new two-dimensional (2D) Semiconductors with high carrier mobilities is highly desirable for material innovation, especially when the configuration has novel topological properties. Here, we proposed a first-principles-based design of a 2D crystal, namely a Be2N6 monolayer. In which, each N atom is shared by two neighboring N atoms and one Be atom, forming a novel moiety of benzene-like N6 rings. Rather than the instability of hexazine, the Be2N6 monolayer has a moderate cohesive energy, good kinetic and thermodynamic stability, due to the stabilization effect of the Be element by forming twelve classical two-centre–two-electron (2c–2e) σ-bonds and five multicenter 6c–2e π-bonds. There are ten π electrons in a unit cell, which satisfies the Huckel rule [4n + 2] (n = 2), indicating the Be2N6 monolayer aromaticity. As a result, the Be2N6 monolayer has an ultra-high mechanical strength of up to 200 J m−2. Particle-swarm optimization (PSO) computations reveal that a cyclo-N6-containing Be2N6 monolayer is the lowest-energy configuration in 2D forms with a stoichiometry of 1 : 3, and therefore could be synthesized experimentally. Furthermore, the Be2N6 monolayer is an Indirect Semiconductor with a band gap of 1.71 eV at the hybrid functional level, close to that of the bulk amorphous silicon ∼1.6 eV widely used in solar cells. At this point, the high electron mobility of up to ∼104 cm2 V−1 s−1 and visible-light absorption of ∼105 cm−1 are observed for the Be2N6 monolayer. If realized, it will not only enrich the knowledge of the bonding nature of nitrogen but could also have potential applications in electronics and optoelectronics.
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Benzene-like N 6 Rings in Be 2 N 6 Monolayer: a Stable 2D Semiconductor with High Carrier Mobility
RSC, 2017Co-Authors: Li Feng, Yu Wang, Wu Hong, Liu Zhifa, Aeberhard Urs, Li YafeiAbstract:Designing new two-dimensional (2D) Semiconductors with high carrier mobilities is highly desirable for material innovation, especially when the configuration has novel topological properties. Here, we proposed a first-principles-based design of a 2D crystal, namely a Be2N6 monolayer. In which, each N atom is shared by two neighboring N atoms and one Be atom, forming a novel moiety of benzene-like N6 rings. Rather than the instability of hexazine, the Be2N6 monolayer has a moderate cohesive energy, good kinetic and thermodynamic stability, due to the stabilization effect of the Be element by forming twelve classical two-centre–two-electron (2c–2e) σ-bonds and five multicenter 6c–2e π-bonds. There are ten π electrons in a unit cell, which satisfies the Hückel rule [4n + 2] (n = 2), indicating the Be2N6 monolayer aromaticity. As a result, the Be2N6 monolayer has an ultra-high mechanical strength of up to 200 J m−2. Particle-swarm optimization (PSO) computations reveal that a cyclo-N6-containing Be2N6 monolayer is the lowest-energy configuration in 2D forms with a stoichiometry of 1 : 3, and therefore could be synthesized experimentally. Furthermore, the Be2N6 monolayer is an Indirect Semiconductor with a band gap of 1.71 eV at the hybrid functional level, close to that of the bulk amorphous silicon ∼1.6 eV widely used in solar cells. At this point, the high electron mobility of up to ∼104 cm2 V−1 s−1 and visible-light absorption of ∼105 cm−1 are observed for the Be2N6 monolayer. If realized, it will not only enrich the knowledge of the bonding nature of nitrogen but could also have potential applications in electronics and optoelectronics
F M Peeters - One of the best experts on this subject based on the ideXlab platform.
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introducing novel electronic and magnetic properties in c3n nanosheets by defect engineering and atom substitution
Physical Chemistry Chemical Physics, 2019Co-Authors: Asadollah Bafekry, Saber Farjami Shayesteh, F M PeetersAbstract:Using first-principles calculations the effect of topological defects, vacancies, Stone–Wales and anti-site and substitution of atoms, on the structure and electronic properties of monolayer C3N are investigated. Vacancy defects introduce localized states near the Fermi level and a local magnetic moment. While pristine C3N is an Indirect Semiconductor with a 0.4 eV band gap, with substitution of O, S and Si atoms for C, it remains a Semiconductor with a band gap in the range 0.25–0.75 eV, while it turns into a metal with H, Cl, B, P, Li, Na, K, Be and Mg substitution. With F substitution, it becomes a dilute-magnetic Semiconductor, while with Ca substitution it is a ferromagnetic-metal. When replacing the N host atom, C3N turns into: a metal (H, O, S, C, Si, P, Li and Be), ferromagnetic-metal (Mg), half-metal (Ca) and spin-glass Semiconductor (Na and K). Moreover, the effects of charging and strain on the electronic properties of Na atom substitution in C3N are investigated. We found that the magnetic moment decreases or increases depending on the type and size of strain (tensile or compression). Our study shows how the band gap and magnetism in monolayer C3N can be tuned by introducing defects and atom substitution. The so engineered C3N can be a good candidate for future low dimensional devices.