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Surface graphene guides were interfaced with an array of individual semiconductor quantum dots, whose position was commensurate with the optical guide modes. The surface guide served as a channel for a Field Effect Transistor (FET) while…

Mesoscale and Nanoscale Physics · Physics 2019-07-09 Xin Miao , Haim Grebel

Photoluminescence of graphene quantum dots (GQDs) of shungite, attributed to individual fragments of reduced graphene oxide (rGO), has been studied for the frozen rGO colloidal dispersions in water, carbon tetrachloride, and toluene.…

Mesoscale and Nanoscale Physics · Physics 2015-06-16 B. S. Razbirin , N. N Rozhkova , E. F. Sheka , D. K. Nelson , A. N. Starukhin , A. S. Goryunov

This work demonstrates the unique approach of introducing divacancy imperfections in topological Stone-Wales type defected graphene quantum dots for harvesting both singlet and triplet excitons, essential for fabricating fluorescent organic…

Mesoscale and Nanoscale Physics · Physics 2022-08-09 Tushima Basak , Tista Basak , Alok Shukla

This study investigates optical activity and quantum transport in twisted bilayer graphene (TBG) systems, demonstrating that the former results from spatial dispersion effects. The transfer matrix method is used to solve the propagation of…

Mesoscale and Nanoscale Physics · Physics 2023-05-31 S. Ta Ho , V. Nam Do

Ab-initio calculations based on density functional theory (DFT) have been performed to study the optical properties of pure graphene and have been compared to that of individual boron (B), nitrogen (N) and BN co-doped graphene sheet. The…

Mesoscale and Nanoscale Physics · Physics 2020-05-22 Pooja Rani , Girija S Dubey , V. K. Jindal

The optical conductivity of freely suspended graphene was examined under non-equilibrium conditions using femtosecond pump-probe spectroscopy. We observed a conductivity transient that varied strongly with the electronic temperature,…

Mesoscale and Nanoscale Physics · Physics 2013-06-20 Leandro M. Malard , Kin Fai Mak , A. H. Castro Neto , N. M. R. Peres , Tony F. Heinz

The optical properties of dielectric plates coated with gapped graphene are investigated on the basis of first principles of quantum electrodynamics. The reflection coefficients and reflectivities of graphene-coated plates are expressed in…

Materials Science · Physics 2017-01-27 G. L. Klimchitskaya , V. M. Mostepanenko

Graphene is an attractive material for broadband photodetection but suffers from weak light absorption. Coating graphene with quantum dots can significantly enhance light absorption and create extraordinarily high photo gain. This high gain…

Mesoscale and Nanoscale Physics · Physics 2020-12-04 Kaixiang Chen , Chufan Zhang , Xiaoxian Zang , Fuyuan Ma , Yuanzhen Chen , Yaping Dan

We theoretically investigate the electronic and magneto-optical properties of rectangular, hexangular, and triangular monolayer phosphorene quantum dots (MPQDs) utilizing the tight-binding method. The electronic states, density of states,…

Mesoscale and Nanoscale Physics · Physics 2015-12-10 Rui Zhang , X. Y. Zhou , D. Zhang , W. K. Lou , F. Zhai , Kai Chang

The unconventional properties of graphene, with a massless Dirac band dispersion and large coherence properties, have raised a large interest for applications in nanoelectronics. In this work, we emphasize that graphene two dimensional…

Mesoscale and Nanoscale Physics · Physics 2008-08-27 Pierre Darancet , Valerio Olevano , Didier Mayou

We study conductance across a twisted bilayer graphene coupled to single-layer graphene leads in two setups: a flake of graphene on top of an infinite graphene ribbon and two overlapping semi-infinite graphene ribbons. We find conductance…

Mesoscale and Nanoscale Physics · Physics 2020-07-30 Hadi Z. Olyaei , Bruno Amorim , Pedro Ribeiro , Eduardo V. Castro

Considerable efforts have been made to trap massless Dirac fermions in graphene monolayer, but only quasi-bound states are realized in continuous graphene sheets up to now. Here, we demonstrate the realization of bound states in nanoscale…

Mesoscale and Nanoscale Physics · Physics 2017-04-05 Jia-Bin Qiao , Hua Jiang , Haiwen Liu , Hong Yang , Ning Yang , Kai-Yao Qiao , Lin He

We have carried out first-principles calculations on electronic properties of graphene quantum dots embedded in hexagonal boron nitride monolayer sheets. The calculations with density functional theory show that the band gaps of quantum…

Mesoscale and Nanoscale Physics · Physics 2015-05-20 Junwen Li , Vivek B. Shenoy

We use an efficient projection scheme for the Fock operator to analyze the size dependence of silicon quantum dots (QDs) electronic properties. We compare the behavior of hybrid, screened hybrid and local density functionals as a function…

Chemical Physics · Physics 2018-04-06 Dor Gabay , Xueyang Wang , Vitaly Lomakin , Amir Boag , Manish Jain , Amir Natan

We present realistic simulations of quantum confinement effects in ballistic graphene quantum dots with linear dimensions of 10 to 40 nm. We determine wavefunctions and energy level statistics in the presence of disorder resulting from edge…

Mesoscale and Nanoscale Physics · Physics 2009-03-18 F. Libisch , C. Stampfer , J. Burgdörfer

Laterally localized electronic states are identified on a single layer of graphene on ruthenium. The individual states are separated by 3 nm and comprise regions of about 90 carbon atoms. This constitutes a quantum dot array, evidenced by…

Materials Science · Physics 2010-07-08 H. G. Zhang , H. Hu , Y. Pan , J. H. Mao , M. Gao , H. M. Guo , S. X. Du , T. Greber , H. -J. Gao

We examine quantum transport in periodic quantum graphs with a vertex coupling non-invariant with respect to time reversal. It is shown that the graph topology may play a decisive role in the conductivity properties illustrating this claim…

Mathematical Physics · Physics 2020-05-20 Pavel Exner , Jiri Lipovsky

The flexibility and effectiveness of message passing based graph neural networks (GNNs) induced considerable advances in deep learning on graph-structured data. In such approaches, GNNs recursively update node representations based on their…

Machine Learning · Computer Science 2023-05-04 Yeskendir Koishekenov , Erik J. Bekkers

The properties of polycrystalline materials are often dominated by the size of their grains and by the atomic structure of their grain boundaries. These effects should be especially pronounced in 2D materials, where even a line defect can…

We theoretically study the optical absorption property of twisted bilayer graphenes with various stacking geometries, and demonstrate that the spectroscopic characteristics serve as a fingerprint to identify the rotation angle between two…

Mesoscale and Nanoscale Physics · Physics 2013-05-21 Pilkyung Moon , Mikito Koshino