Long wavelength optical response of graphene-MoS2 heterojunction

Joon Young Kwak, Jeonghyun Hwang, Brian Calderon, Hussain Alsalman, Michael G. Spencer

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Abstract

The optical response of graphene-MoS2 heterojunctions is investigated. Spatial resolution photoresponse maps obtained using multiple bias conditions are measured and analyzed by exciting the graphene-MoS2 heterojunction area, MoS2, and Ti-MoS2 junction on the same device with an 800 nm wavelength Ti-Sapphire raster scanning laser. It is found that a large photothermal electric (PTE) effect is the dominant mechanism for photoresponse in a graphene-MoS2 heterojunction. Responsivities of 0.139 mA/W and 0.019 mA/W on the graphene-MoS2 heterojunction area and 0.457 mA/W and 0.032 mA/W on the Ti-MoS2 junction area are observed with and without a bias, respectively, using a 430 μW laser. Current enhancement due to laser illumination is observed as far as 14 μm from the edge of the graphene-MoS2 heterojunction. Voltage generated by the PTE effect lowers the Schottky barrier junction, enabling more current flow during laser excitation. Photothermal-generated voltages of 0.22-0.47 mV and 31.8-37.9 mV are estimated at the graphene-MoS2 heterojunction and the Ti-MoS2 junction, respectively.

Original languageEnglish
Article number091108
JournalApplied Physics Letters
Volume108
Issue number9
DOIs
StatePublished - 29 Feb 2016

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© 2016 AIP Publishing LLC.

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