Near Field Photoluminescence Imaging of Monolayer Heterojunction of Lateral WS2-MoS2 .
He-Chun Chou (周和均)1, Chun-Te Sung (宋俊德)1,2, Xin-Quan Zhang (張鋅權)2, E. C. Lin (林爾鎮)2, Yi-Hsein Lee (李奕賢)2, Chi Chen (陳祺)1*
1Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
2Department of Materials Science and Engineering, National Tsing Hua Univeristy, Hsinchu, Taiwan
* Presenter:Chi Chen (陳祺)
Heterostructure of vertical or lateral stacking of various two-dimensional (2D) materials, including transition metal dichalcogenides (TMD), graphene, and BN, potentially enable engineering of band alignments and next generation nano-devices for real applications. With well-developed exfoliation and transfer techniques, optoelectronic properties of stacked vertical heterosturcutres have become popular research topics. However, lateral heterojunction of 2D lattices with ideal hetero-interfaces remains a challenging issue and become a burgeoning field due to a lack of insufficient optical resolution to probe the hetero-interfaces in atomic resolution . Here we investigate CVD-grown monolayer heterojunction of the lateral WS2-MoS2 . Scanning near-field optical microscopy (SNOM) is adopted to probe local photoluminescence (PL) simultaneously with AFM topography. With ~70 nm SNOM-PL resolution, anomalous PL depletion and bunching was observed within the width of 200 nm across the heterojunction boundary. Localized PL suggests that exciton generation and recombination is strongly affected by the steep distribution of electrical field caused by the band alignment of the heterojunction .

Keywords: near field optical microscopy, WS2-MoS2 heterojunction, 2D materials, photoluminescence