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Photosensor Device Based on Few-Layered WS2 Films

Authors

  • Néstor Perea-López,

    1. Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
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  • Ana Laura Elías,

    1. Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
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  • Ayse Berkdemir,

    1. Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
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  • Andres Castro-Beltran,

    1. Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
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  • Humberto R. Gutiérrez,

    1. Department of Physics & Astronomy, University of Louisville, Louisville, KY 40292, USA
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  • Simin Feng,

    1. Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
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  • Ruitao Lv,

    1. Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
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  • Takuya Hayashi,

    1. Research Center for Exotic Nanocarbons (JST), Shinshu University, Wakasato 4-17-1, Nagano 380-853, Japan
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  • Florentino López-Urías,

    1. Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
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  • Sujoy Ghosh,

    1. Department of Physics, Southern Illinois University Carbondale, IL 62901, USA
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  • Baleeswaraiah Muchharla,

    1. Department of Physics, Southern Illinois University Carbondale, IL 62901, USA
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  • Saikat Talapatra,

    1. Department of Physics, Southern Illinois University Carbondale, IL 62901, USA
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  • Humberto Terrones,

    1. Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
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  • Mauricio Terrones

    Corresponding author
    1. Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA
    2. Research Center for Exotic Nanocarbons (JST), Shinshu University, Wakasato 4-17-1, Nagano 380-853, Japan
    3. Department of Chemistry, Department of Materials Science and Engineering and Materials, Research Institute, The Pennsylvania State University, University Park, PA 16802, USA
    • Department of Physics and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, PA 16802, USA.

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Abstract

Few-layered films of WS2, synthesized by chemical vapor deposition on quartz, are successfully used as light sensors. The film samples are structurally characterized by Raman spectroscopy, atomic force microscopy, scanning electron microscopy, and high-resolution transmission electron microscopy. The produced samples consist of few layered sheets possessing up to 10 layers. UV–visible absorbance spectra reveals absorption peaks at energies of 1.95 and 2.33 eV, consistent with the A and B excitons characteristic of WS2. Current–voltage (IV) and photoresponse measurements carried out at room temperature are performed by connecting the WS2 layered material with Au/Ti contacts. The photocurrent measurements are carried out using five different laser lines ranging between 457 and 647 nm. The results indicate that the electrical response strongly depends on the photon energy from the excitation lasers. In addition, it is found that the photocurrent varies non-linearly with the incident power, and the generated photocurrent in the WS2 samples varies as a squared root of the incident power. The excellent response of few-layered WS2 to detect different photon wavelengths, over a wide range of intensities, makes it a strong candidate for constructing novel optoelectronic devices.

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