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- Islam, Shadli, et al.
(författare)
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Ab-initio Calculation of Nonlinear Optical Susceptibilities in Germanium Quantum Dots
- 2019
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Ingår i: 2018 IEEE 13TH NANOTECHNOLOGY MATERIALS AND DEVICES CONFERENCE (NMDC). - 2378-377X. - 9781538610169 ; , s. 113-116
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Konferensbidrag (refereegranskat)abstract
- Using Time Independent Density Functional Theory (TIDFT) implemented in SIESTA (R) we calculated the 2nd order and 3rd order nonlinear optical susceptibilities of small Germanium Quantum Dots (GeQD). We observe that the symmetry breaking due to surface termination enhances chi((2)) up to 299.1 pm/V which promises a strong Second Harmonic Generation (SHG) in GeQDs. Diagonal components for chi((2)) tensor are 52.5, 11.2, 299.1 pm/V, for xxx, yyy and zzz, respectively. The 3rd order susceptibility, chi((3)), is within the range of (0.2-0.4) x 10(-18) m(2)/V-2 which is close to the reported experimental values of bulk Germanium. This study suggests possibilities of enhancing SHG in GeQDs through symmetry breaking via strain and surface termination/reconstruction as well as suitability of this fast and less-computationally intensive Density Functional Theory (DFT)-based method in predicting nonlinear optical susceptibilities of nano structures.
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| 2. |
- Shiri, Daryoush, 1975, et al.
(författare)
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An Electrically Controlled Heat Rectifier using Graphene Nanoribbons
- 2019
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Ingår i: 2019 IEEE 14th Nanotechnology Materials and Devices Conference, NMDC 2019. - 2378-377X. - 9781728126371 ; October 2019, s. 1-4
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Konferensbidrag (refereegranskat)abstract
- Using Molecular Dynamics (MD) simulations we propose that splitting a graphene nanoribbon into two unequal strained sections using external force leads to large asymmetry in the forward and reverse heat fluxes. We find that the corresponding rectification ratio (RR) is enhanced to 60% compared to previous proposals. More importantly, the polarity of the proposed heat diode is controllable on-the-fly i.e. by changing the position where force is applied. This technique obviates the complex nano-patterning and lithography required to pattern graphene every time a new rectification value or sign is sought for and opens a route to simpler fabrication of phononic devices in 2D materials.
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