Highly efficient gate-tunable photocurrent generation in vertical heterostructures of layered materials

1] Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, USA [2] Department of Electronic and Electrical Engineering, Sungkyunkwan University, Suwon 440-746, Republic of Korea [3] Center for Integrated Nanostructure Physics, Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746, Republic of Korea.
Nature Nanotechnology (Impact Factor: 34.05). 10/2013; 8(12). DOI: 10.1038/nnano.2013.219
Source: PubMed


Layered materials of graphene and MoS2, for example, have recently emerged as an exciting material system for future electronics and optoelectronics. Vertical integration of layered materials can enable the design of novel electronic and photonic devices. Here, we report highly efficient photocurrent generation from vertical heterostructures of layered materials. We show that vertically stacked graphene-MoS2-graphene and graphene-MoS2-metal junctions can be created with a broad junction area for efficient photon harvesting. The weak electrostatic screening effect of graphene allows the integration of single or dual gates under and/or above the vertical heterostructure to tune the band slope and photocurrent generation. We demonstrate that the amplitude and polarity of the photocurrent in the gated vertical heterostructures can be readily modulated by the electric field of an external gate to achieve a maximum external quantum efficiency of 55% and internal quantum efficiency up to 85%. Our study establishes a method to control photocarrier generation, separation and transport processes using an external electric field.

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    • "In particular, remarkable progress has been made for MoS 2 photodetectors: MoS 2 photoconductors exhibit a high responsivity of 880 A/W [31]; chemically doped MoS 2 p-n junctions exhibit a good detectivity of 1010 at 1.5 V [32]; combined with graphene [33] and WSe 2 [34], MoS 2 vertical heterojunctions exhibit external quantum efficiencies (EQEs) of 55% and 34%, respectively . In parallel with these efforts, emerging 2D GaTe photoconductors with good photosensitivity were reported recently [35], suggesting another appealing use of 2D materials for optoelectronic applications. "
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