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Title: Electro-absorption of silicene and bilayer graphene quantum dots

Abstract

We study numerically the optical properties of low-buckled silicene and AB-stacked bilayer graphene quantum dots subjected to an external electric field, which is normal to their surface. Within the tight-binding model, the optical absorption is calculated for quantum dots, of triangular and hexagonal shapes, with zigzag and armchair edge terminations. We show that in triangular silicene clusters with zigzag edges a rich and widely tunable infrared absorption peak structure originates from transitions involving zero energy states. The edge of absorption in silicene quantum dots undergoes red shift in the external electric field for triangular clusters, whereas blue shift takes place for hexagonal ones. In small clusters of bilayer graphene with zigzag edges the edge of absorption undergoes blue/red shift for triangular/hexagonal geometry. In armchair clusters of silicene blue shift of the absorption edge takes place for both cluster shapes, while red shift is inherent for both shapes of the bilayer graphene quantum dots.

Authors:
 [1];  [2];  [3];  [1];  [4];  [5];  [5];  [6]
  1. Laboratory of Condensed Matter Physics, University of Picardie, Amiens 80039 (France)
  2. (Egypt)
  3. Physics Department, Faculty of Science, Ain Shams University, Cairo (Egypt)
  4. (Russian Federation)
  5. School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL (United Kingdom)
  6. (Belarus)
Publication Date:
OSTI Identifier:
22597889
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 120; Journal Issue: 1; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ABSORPTION; ELECTRIC FIELDS; GEOMETRY; GRAPHENE; LAYERS; OPTICAL PROPERTIES; PEAKS; QUANTUM DOTS; RED SHIFT; SHAPE; SILICENE; SURFACES

Citation Formats

Abdelsalam, Hazem, E-mail: hazem.abdelsalam@etu.u-picardie.fr, Department of Theoretical Physics, National Research Center, Cairo 12622, Talaat, Mohamed H., Lukyanchuk, Igor, L. D. Landau Institute for Theoretical Physics, Moscow, Portnoi, M. E., Saroka, V. A., E-mail: v.saroka@exeter.ac.uk, and Institute for Nuclear Problems, Belarusian State University, Bobruiskaya 11, 220030 Minsk. Electro-absorption of silicene and bilayer graphene quantum dots. United States: N. p., 2016. Web. doi:10.1063/1.4955222.
Abdelsalam, Hazem, E-mail: hazem.abdelsalam@etu.u-picardie.fr, Department of Theoretical Physics, National Research Center, Cairo 12622, Talaat, Mohamed H., Lukyanchuk, Igor, L. D. Landau Institute for Theoretical Physics, Moscow, Portnoi, M. E., Saroka, V. A., E-mail: v.saroka@exeter.ac.uk, & Institute for Nuclear Problems, Belarusian State University, Bobruiskaya 11, 220030 Minsk. Electro-absorption of silicene and bilayer graphene quantum dots. United States. doi:10.1063/1.4955222.
Abdelsalam, Hazem, E-mail: hazem.abdelsalam@etu.u-picardie.fr, Department of Theoretical Physics, National Research Center, Cairo 12622, Talaat, Mohamed H., Lukyanchuk, Igor, L. D. Landau Institute for Theoretical Physics, Moscow, Portnoi, M. E., Saroka, V. A., E-mail: v.saroka@exeter.ac.uk, and Institute for Nuclear Problems, Belarusian State University, Bobruiskaya 11, 220030 Minsk. 2016. "Electro-absorption of silicene and bilayer graphene quantum dots". United States. doi:10.1063/1.4955222.
@article{osti_22597889,
title = {Electro-absorption of silicene and bilayer graphene quantum dots},
author = {Abdelsalam, Hazem, E-mail: hazem.abdelsalam@etu.u-picardie.fr and Department of Theoretical Physics, National Research Center, Cairo 12622 and Talaat, Mohamed H. and Lukyanchuk, Igor and L. D. Landau Institute for Theoretical Physics, Moscow and Portnoi, M. E. and Saroka, V. A., E-mail: v.saroka@exeter.ac.uk and Institute for Nuclear Problems, Belarusian State University, Bobruiskaya 11, 220030 Minsk},
abstractNote = {We study numerically the optical properties of low-buckled silicene and AB-stacked bilayer graphene quantum dots subjected to an external electric field, which is normal to their surface. Within the tight-binding model, the optical absorption is calculated for quantum dots, of triangular and hexagonal shapes, with zigzag and armchair edge terminations. We show that in triangular silicene clusters with zigzag edges a rich and widely tunable infrared absorption peak structure originates from transitions involving zero energy states. The edge of absorption in silicene quantum dots undergoes red shift in the external electric field for triangular clusters, whereas blue shift takes place for hexagonal ones. In small clusters of bilayer graphene with zigzag edges the edge of absorption undergoes blue/red shift for triangular/hexagonal geometry. In armchair clusters of silicene blue shift of the absorption edge takes place for both cluster shapes, while red shift is inherent for both shapes of the bilayer graphene quantum dots.},
doi = {10.1063/1.4955222},
journal = {Journal of Applied Physics},
number = 1,
volume = 120,
place = {United States},
year = 2016,
month = 7
}
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  • Highlights: Black-Right-Pointing-Pointer We seek to compare the optical behavior of coupled bilayer and multilayer QDs. Black-Right-Pointing-Pointer The coupled InAs/GaAs QD stacks are grown by Stranski-Krastanow growth technique. Black-Right-Pointing-Pointer We comment on roles of vertical strain and electronic coupling along the stacks. -- Abstract: Coupled InAs/GaAs quantum dots have generated an interest for their longer emission wavelength and narrower line-width. However, a consensus has not been reached on the parameters of growth required to achieve a desired effect from coupling due to contradictory reports of shorter emission wavelengths. In this paper, we seek to compare the luminescence properties of bilayer quantummore » dots (BQDs) with those of multilayer quantum dots (MQDs), grown at a very low deposition rate, keeping all parameters constant. The BQD and MQD samples were grown by solid source MBE at a slow growth rate of 0.03 ML/s. A blueshift in the PL spectra for 11 layer coupled InAs/GaAs MQD heterostructure is observed compared to the BQDs for temperatures less than 180 K. This undesired blueshift is attributed to strain in the structure which overshadowed the usual redshift in emission wavelength in such structures due to electronic coupling. The variation in PL line-width with temperature in the MQD structure is found to be much lower than in the BQD. However the PL intensity of the MQDs fall at a faster rate with temperature compared to the BQD sample, due to strain generated non-radiative centers in the islands which favors in thermalization of carriers.« less