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We analyse the electronic and optical properties of graphene quantum dots (GQD) using accurate \textit{ab initio} many-body $GW$ and Bethe-Salpeter calculations. We show that most pristine GQD, including structures with irregular shapes,…

Mesoscale and Nanoscale Physics · Physics 2020-03-26 Denis M. Basko , Ivan Duchemin , Xavier Blase

We demonstrate that optical transparency of any two-dimensional system with a symmetric electronic spectrum is governed by the fine structure constant and suggest a simple formula that relates a quasi-particle spectrum to an optical…

Mesoscale and Nanoscale Physics · Physics 2010-07-22 V. G. Kravets , A. N. Grigorenko , R. R. Nair , P. Blake , S. Anissimova , K. S. Novoselov , A. K. Geim

In this paper, optical and electronic properties of diamond shaped graphene quantum dots (DQDs) have been studied by employing large-scale electron-correlated calculations. The computations have been performed using the \pi-electron…

Mesoscale and Nanoscale Physics · Physics 2015-11-16 Tista Basak , Himanshu Chakraborty , Alok Shukla

We develop the tight-binding model to study electronic and optical properties of graphane. The strong sp3 chemical bondings among the carbon and hydrogen atoms induce a special band structure and thus lead to the rich optical excitations.…

Materials Science · Physics 2016-10-31 M. H. Lee , H. C. Chung , J. M. Lu , C. P. Chang , M. F. Lin

Biased bilayer graphene, with its easily tunable band gap, presents itself as the ideal system to explore the excitonic effect in graphene based systems. In this paper we study the excitonic optical response of such a system by combining a…

Mesoscale and Nanoscale Physics · Physics 2022-01-20 J. C. G. Henriques , Itai Epstein , N. M. R. Peres

Due to the advantage of tunability via size, shape, doping and relatively low level of loss and high extent of spatial confinement, graphene quantum dots (GQDs) are emerging as an effective way to control light by molecular engineering. The…

Materials Science · Physics 2015-02-13 Sharma S. R. K. C Yamijala , Madhuri Mukhopadhyay , Swapan K. Pati

In this paper, optical properties of Chiral Graphene Nanoribbons both in longitude and transverse polarization have been studied using density functional theory calculation. It has been shown that the selection rule which have been reported…

Mesoscale and Nanoscale Physics · Physics 2012-05-22 M. Berahman , M. Asad , M. H. Sheikhi

We report exact diagonalization studies of inelastic light scattering in few-electron quantum dots under the strong confinement regime characteristic of self-assembled dots. We apply the orthodox (second-order) theory for scattering due to…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 Alain Delgado , Adriel Dominguez , Ricardo Perez , D. J. Lockwood , Augusto Gonzalez

Motivated by recent advances in fabricating graphene nanostructures, we find that an electron can be trapped in Z-shaped graphene nanoconstriction with zigzag edges. The central section of the constriction operates as a single-level quantum…

Mesoscale and Nanoscale Physics · Physics 2010-09-23 Adam Rycerz

In this paper, we study theoretically the electron and spectral properties of Ge1-xSnx systems, including alloys, cubic- and spherical quantum dots. The single-particle electron and hole states are calculated within the sp3d5s*…

Mesoscale and Nanoscale Physics · Physics 2024-06-21 Krzysztof Gawarecki , Jakub Ziembicki , Paweł Scharoch , Robert Kudrawiec

Density functional theory calculations are performed on phosphorene quantum dots having different shapes and edge terminations to investigate their structure stability, electronic properties, and gas sensing ability. All the selected…

Mesoscale and Nanoscale Physics · Physics 2018-12-05 Hazem Abdelsalam , Vasil A. Saroka , Waleed O. Younis

We address the electronic properties of quantum dots in the two-dimensional $\alpha-\mathcal{T}_3$ lattice when subjected to a perpendicular magnetic field. Implementing an infinite mass boundary condition, we first solve the eigenvalue…

Mesoscale and Nanoscale Physics · Physics 2020-09-08 Alexander Filusch , Holger Fehske

The electronic and optical properties of graphene nanoribbons under uniaxial periodic strain have been explored using various nearest-neighbor hopping patterns. It is found that by properly selecting hopping patterns, momentum-resolved gaps…

Mesoscale and Nanoscale Physics · Physics 2024-11-05 Chunwen Zhang , W. X. Yan

We consider a square lattice configuration of circular gate-defined quantum dots in an unbiased graphene sheet and calculate the electronic, particularly spectral properties of finite albeit actual sample sized systems by means of a…

Mesoscale and Nanoscale Physics · Physics 2015-06-19 A. Pieper , R. L. Heinisch , G. Wellein , H. Fehske

Interband absorption and luminescence of quasi-two-dimensional, circularly symmetric, N_e electron quantum dots are studied at high magnetic fields, 8<B<60 T, and low temperatures, T<<2 K. In the N_e=0 and 1 dots, the initial and final…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Augusto Gonzalez , Eduardo Menendez-Proupin

A review work is done for electronic and optical properties of graphene nanoribbons in magnetic, electric, composite, and modulated fields. Effects due to the lateral confinement, curvature, stacking, non-uniform subsystems and hybrid…

Mesoscale and Nanoscale Physics · Physics 2016-03-10 Hsien-Ching Chung , Cheng-Peng Chang , Chiun-Yan Lin , Ming-Fa Lin

We suggest a way of confining quasiparticles by an external potential in a small region of a graphene strip. Transversal electron motion plays a crucial role in this confinement. Properties of thus obtained graphene quantum dots are…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 P. G. Silvestrov , K. B. Efetov

We study electronic and optical properties of single layer phosphorene quantum dots with various shapes, sizes, and edge types (including disordered edges) subjected to an external electric field normal to the structure plane. Compared to…

Mesoscale and Nanoscale Physics · Physics 2017-08-29 V. A. Saroka , I. Lukyanchuk , M. E. Portnoi , H. Abdelsalam

Optical transitions in a semiconductor quantum dot are theoretically investigated, with emphasis on the coupling to longitudinal optical phonons, and including excitonic effects. When limiting to a finite number of $m$ electron and $n$ hole…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 T. Stauber , R. Zimmermann

We present quantum-mechanical density-matrix formalism for calculating the nonlinear optical response of magnetized graphene, valid for arbitrarily strong magnetic and optical fields. We show that magnetized graphene possesses by far the…

Mesoscale and Nanoscale Physics · Physics 2015-05-30 Xianghan Yao , Alexey Belyanin