• Journal of Semiconductors
  • Vol. 40, Issue 6, 062006 (2019)
Xiaowei Jiang1、2
Author Affiliations
  • 1College of Information Engineering, Quzhou College of Technology, Quzhou 32400, China
  • 2Laboratory of Opto-Electronics Technology, College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124, China
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    DOI: 10.1088/1674-4926/40/6/062006 Cite this Article
    Xiaowei Jiang. Broadband absorption of graphene from magnetic dipole resonances in hybrid nanostructure[J]. Journal of Semiconductors, 2019, 40(6): 062006 Copy Citation Text show less

    Abstract

    As emerging new material, graphene has inspired great research interest. However, most of the studies focused on how to improve the absorption efficiency of graphene, but payed little attention on broadening absorption bandwidth while ensuring high absorption efficiency. In this work, we proposed a hybrid nanostructure, which not only can improve absorption efficiency but also can increase absorption bandwidth. The proposed hybrid nanostructure consists of a monolayer graphene sandwiched between three Ag gratings with different widths and a SiO2 spacer on a Ag substrate, these three gratings and substrate can excite three independent magnetic dipole resonances. In our calculations, we numerically demonstrate the proposed hybrid structure can achieve graphene absorption bandwidth of 0.311 μm in near-infrared region with absorption exceeding 30% . We also studied absorption peaks dependence on gratings widths and SiO2 spacer thickness, and explained the results using physical mechanism. Our research can provide a theoretical guidance for future device preparation.
    ${\varepsilon _{{\rm{Ag}}}}={\rm{ 3.4}}-\frac{{\omega _{\rm{p}}^{\rm{2}}}}{{{\omega ^{\rm{2}}}-{\rm{ i}}\omega \gamma }}.$(1)

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    ${\sigma _{\operatorname{intra}}}{\rm{ = }}\frac{{{\rm{i}}{{\rm e}^2}{k_{\rm B}}T}}{{\pi {\hbar ^2}(\omega +\ {\rm{i}}\varGamma )}}\left[ {\frac{{{\mu _{\rm c}}}}{{{k_{\rm B}}T}} + 2\ln ({{\rm e}^{\frac{{ - {\mu _{\rm c}}}}{{{k_{\rm B}}T}}}} + 1)} \right],$(2)

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    ${\sigma _{\rm inter}} = \frac{{i{e^2}}}{{4\pi \hbar }}\ln \left[ {\frac{{2{\mu _{\rm c}} - \left( {\omega + {\rm{i}}{\rm{2}}\varGamma } \right)\hbar }}{{2{\mu _{\rm c}} + (\omega + {\rm{i}}{\rm{2}}\varGamma )\hbar }}} \right],$(3)

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    ${\varepsilon _g} = 1 + {\rm{i}}\frac{\sigma }{{\omega {\varepsilon _0}{t_g}}},$(4)

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    $ {\lambda _{{\rm{MP}}}}={\rm{ 2}}\pi {c_0}\sqrt {({L_{\rm m}} + {L_{\rm e}})C} , $ (5)

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    Xiaowei Jiang. Broadband absorption of graphene from magnetic dipole resonances in hybrid nanostructure[J]. Journal of Semiconductors, 2019, 40(6): 062006
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