▎ 摘　　要

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 0.032mA/W on the Ti-MoS2 junction area are observed with and without a bias, respectively, using a 430 mu W laser. Current enhancement due to laser illumination is observed as far as 14 mu m 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. (C) 2016 AIP Publishing LLC.