Optical Properties of Gated Bilayer Graphene Quantum Dots with Trigonal Warping
ORAL
Abstract
We study the effects of trigonal warping on the optical properties of gated lateral bilayer graphene (BLG)[1-5] quantum dots (QDs) where both electrons and holes are confined by applied voltages. Building upon previous work [1,2], we employ an atomistic tight-binding model to compute the single-particle QD states and analyze how trigonal warping influences the wavefunctions and energy spectrum as a function of the applied vertical electric field and quantum dot confining potential. We obtain the dipole matrix elements and analyze the impact of trigonal warping and electric field on the oscillator strengths. Furthermore, we incorporate the electron-electron interactions by computing the microscopic Coulomb matrix elements, self-energies, and electron-hole direct attraction and exchange repulsion and solve the Bethe-Salpeter equation to obtain the excitonic absorption spectrum[1,3-5]. Our results reveal an increase in the amplitude of absorption peaks for the low energy exciton states as compared to the case where trigonal warping is neglected, similar to that found in biased BLG encapsulated in hexagonal boron nitride [3-5]. Finally, we compute the absorption spectrum as a function of vertical electric field and lateral quantum dot potential that further amplifies the effects of trigonal warping on the optical properties. This has the potential to tune both bright and dark peaks in the excitonic absorption spectrum, yielding a variety of applications in quantum information [3], storage, detection [1], and voltage-tunable emission properties in the THz photon energy range [4].
*This research was supported by NSERC Discovery Grant No. RGPIN 2019-05714, the QSP-078 project of the Quantum Sensors Program at the National Research Council of Canada, University of Ottawa Research Chair in Quantum Theory of Materials, Nanostructures, and Devices., and Digital Research Alliance Canada with computing resources.
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Publication:[1] Y. Saleem, K. Sadecka, M. Korkusinski, D. Miravet, A. Dusko and P. Hawrylak, Nano Letters 23, 2998–3004 (2023). [2] M. Korkusinski, Y. Saleem, A. Dusko, D. Miravet and P. Hawrylak, Nano Letters 23, 7546-7551 (2023). [3] J. C. G. Henriques, I. Epstein, and N. M. R. Peres, Physical Review B 105, 045411 (2022). [4] M. O. Sauer and T. G. Pedersen, Physical Review B 105, 115416 (2022). [5] L. Ju, L. Wang, T. Cao, T. Taniguchi, K. Watanabe, S. G. Louie, F. Rana, J. Park, J. Hone, F. Wang, P. L. McEuen, Science 358, 907– 910 (2017).
