Ultraviolet Photoresponse Enhancement of Graphene/Al_xO_y-NPs/MoS₂ Heterostructure Photodetectors

Molybdenum disulfide (MoS2) has been widely used to fabricate the photodetectors in recent years due to its excellent optical properties. However, the narrow detection bandwidth of MoS2 films limits their applications. Here, a thin Al film was deposited on the surface of MoS2 and naturally oxidized to form the AlxOy nanoparticles (AlxOy-NPs) for the enhanced performance of graphene/AlxOy-NPs/MoS2 heterostructure photodetectors. The material analyses were performed to confirm the formation of AlxOy-NPs on MoS2 and its influence on light absorption. Additionally, the photoresponse of graphene/AlxOy-NPs/MoS2 heterostructure photodetectors was investigated, and found that the localized surface plasmon resonance (LSPR) was induced in the ultraviolet-A (UV-A) band (365 nm), increasing the photocurrent owing to the p-type nature of graphene channel with the recombination of excited electrons from AlxOy-NPs/MoS2 to enhance the photoresponse. The photodetectors with an AlxOy film of 0.5 nm presented a UV-A light detection capability with the photoresponsivity, quantum efficiency, and detectivity of 6.24 A/W, 2120%, and $1.79\times 10^{{10}}$ Jones, respectively, at the optical power of 10 mW/cm2. Thus, the proposed one-step growth method of AlxOy-NPs on MoS2 films to fabricate the graphene/AlxOy-NPs/MoS2 heterostructure photodetectors with excellent photoresponse can facilitate the development of novel 2-D material photodetectors in future.