Neo-heterojunction based on the kesterite copper chalcogenide semiconductor with magnetic iron-cation partial-substitution: In-situ room-temperature pulsed laser deposition and optoelectronic properties

For improving optoelectronic properties of copper chalcogenide semiconductors such as Cu2ZnSnS4 (CZTS), we explore to optimize CZTS itself and construct heterostructures on the perspective of semiconductor device design. Specifically, in order to suppress widely existed CuZn and ZnCu antisite defects of pure CZTS, we synthesize 25%-Fe-doped CZTS (CZFTS) thin films through partial substitution of magnetic iron for zinc; we further integrate electron acceptor Bi2S3 to CZFTS and constitute CZFTS/Bi2S3 heterostructure. Our newly-developed in-situ room-temperature pulsed laser deposition (PLD) technique is adopted to prepare the bilayer sulfide films without post-sulfurization process, effectively optimizing CZFTS-Bi2S3 interfaces. Chronoamperometric measurements demonstrate that CZFTS/Bi2S3 heterojunction has at least one order-of-magnitude improvement in photoelectric response speed within visible light (Vis) region compared to single CZFTS film, and responding time is decreased to a few milliseconds. Hereby, the synergistically combining partial cation substitution and in-situ PLD technique is promising to develop the Vis-active CZTS-based thin-film photodetectors in an effective and efficient way as well as to economically produce such analogous thin-film photoelectric devices based on polynary chalcogenide.