Modulation of the carrier concentration and electronic type of monolayer (1L) MoS2 is highly important for applications in logic circuits, solar cells, and light-emitting diodes. Here, we demonstrate the tuning of the electronic properties of large-area 1L-MoS2 using graphene oxide (GO). GO sheets are well-known as hole injection layers since they contain electron-withdrawing groups such as carboxyl, hydroxyl, and epoxy. The optical and electronic properties of GO-treated 1L-MoS2 are dramatically changed. The photoluminescence intensity of GO-treated 1L-MoS2 is increases by more than 470% compared to the pristine sample because of the increase in neutral exciton contribution. In addition, the A1g peak in Raman spectra shifts considerably, revealing that GO treatment led to the formation of p-type doped 1L-MoS2. Moreover, the current vs voltage (I-V) curves of GO-coated 1L-MoS2 field effect transistors show that the electron concentration of 1L-MoS2 is significantly lower in comparison with pristine 1L-MoS2. Current rectification is also observed from the I-V curve of the lateral diode structure with 1L-MoS2 and 1L-MoS2/GO, indicating that the electronic structure of MoS2 is significantly modulated by the electron-withdrawing functional group of GO.
Keywords: Raman spectroscopy; electron-withdrawing effect; graphene oxide; monolayer MoS2; photoluminescence.