Nature of Photoconductivity in Self-Powered Single-Atomic-Layered Nb-Doped WSe2 Phototransistors

초록

Although single-atomic-layered alloys are regarded aspromisingcomponents for improving the performance of broadband photodetectors,the origin of their enhanced photoresponsivity due to the introductionof dopants in the crystal lattice has not yet been investigated indepth. Herein, we comprehensively analyze the nature of the photoconductivityof a photodetector based on a niobium (Nb)-doped WSe2 monolayer.The Nb-doped WSe2 photodetector exhibited superior responsivityand specific detectivity compared with those of the undoped WSe2 photodetectors. Experimental and density functional theoryanalyses revealed that the introduction of Nb not only modified theFermi level of WSe2 but also generated multiple electron-trappingsites, thereby increasing both the photovoltaic and photogating effectsto improve the photocurrent of the device. We believe that this researchpresents a sophisticated approach to achieve photodetectors basedon single-atomic-layered alloys, which are both highly sensitive andenergy-efficient.

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