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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Tuning the electron band structure of graphene for optoelectronics
摘要： Graphene, a conjugated sp2 carbon sheet arranged in a two-dimensional honeycomb-like lattice, shows the unique electronic structure in which conical shaped π-electron conduction and valence bands meet at the Dirac point. The properties of graphene are largely controlled by the Fermi level and the density of π-electron states, which can be used for tuning graphene to specific optoelectronic and electrochemical applications. We report a computational study of the electron states and electrochemical response towards I?/I3 redox mediator used in dye sensitized solar cells. We consider the influence of lattice deformations and magnetic field combined with covalently bonded moieties and charged ions on the heterogeneous electron transfer kinetics.
关键词： uniaxial strain,density of electron states,graphene,heterogeneous electron transfer,Landau levels
更新于2025-09-12 10:27:22
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Confined electron states in two-dimensional HgTe in magnetic field: Quantum dot versus quantum ring behavior
摘要： We investigate the electron states and optical absorption in square- and hexagonal-shaped two-dimensional (2D) HgTe quantum dots and quantum rings in the presence of a perpendicular magnetic field. The electronic structure is modeled by means of the sp3d 5s? tight-binding method within the nearest-neighbor approximation. Both bulklike and edge states appear in the energy spectrum. The bulklike states in quantum rings exhibit Aharonov-Bohm oscillations in magnetic field, whereas no such oscillations are found in quantum dots, which is ascribed to the different topology of the two systems. When magnetic field varies, all the edge states in square quantum dots appear as quasibands composed of almost fully flat levels, whereas some edge states in quantum rings are found to oscillate with magnetic field. However, the edge states in hexagonal quantum dots are localized like in rings. The absorption spectra of all the structures consist of numerous absorption lines, which substantially overlap even for small line broadening. The absorption lines in the infrared are found to originate from transitions between edge states. It is shown that the magnetic field can be used to efficiently tune the optical absorption of HgTe 2D quantum dot and quantum ring systems.
关键词： HgTe,quantum dots,quantum rings,optical absorption,electron states,tight-binding method,magnetic field,Aharonov-Bohm oscillations
更新于2025-09-12 10:27:22