Nano-patterning on multilayer MoS2 via block copolymer lithography for highly sensitive and responsive phototransistors
Heekyeong Park, Jiyoul Lee, Gyuchull Han, AbdulAziz AlMutairi, Young‐Hoon Kim, Jaichan Lee, Young‐Min Kim, Young‐Jun Kim, Youngki Yoon, Sunkook Kim
Abstract
Abstract Indirect bandgap of multilayer molybdenum disulfide has been recognized as a major hindrance to high responsivity of MoS 2 phototransistors. Here, to overcome this fundamental limitation, we propose a structural engineering of MoS 2 via nano-patterning using block copolymer lithography. The fabricated nanoporous MoS 2 , consisting of periodic hexagonal arrays of hexagon nanoholes, includes abundant edges having a zigzag configuration of atomic columns with molybdenum and sulfur atoms. These exposed zigzag edges are responsible for multiple trap states in the bandgap region, as confirmed by photo-excited charge-collection spectroscopy measurements on multilayer nanoporous MoS 2 phototransistors, showing that in-gap states only near the valence band can result in a photogating effect. The effect of nano-patterning is therefore to significantly enhance the responsivity of multilayer nanoporous MoS 2 phototransistors, exhibiting an ultra-high photoresponsivity of 622.2 A W −1 . Our nano-patterning of MoS 2 for photosensing application paves a route to structural engineering of two-dimensional materials for highly sensitive and responsive optoelectronic devices.