Enhanced photoresponsivity of multilayer MoS_2 transistors using high work function MoO_x overlayer

摘要

Using thin sub-stoichiometric molybdenum trioxide (MoO_x, x < 3) overlayer, we demonstrate over 20-folds enhanced photoresponsivity of multilayer MoS_2 field-effect transistor. The fabricated device exhibits field-effect mobility (μ_(FE)) of up to 41.4cm~2/V s and threshold voltage (V_(TH)) of —9.3 V, which is also modulated by the MoO_x overlayer. The MoO_x layer (~25nm), commonly known for a high work function (~6.8 eV) material with a band gap of ~3 eV, is evaporated on top of the MoS_2 channel and confirmed by the transmission electron microscope analysis. The electrical and optical modulation effects are associated with interfacial charge transfer and thus an induced built-in electric field at the MoS_2/MoO_x interface. The results show that high work function MoO_x can be a promising heterostructure material in order to enhance the photoresponse characteristics of MoS_2-based devices.