Zhao, YueYueZhaoTsai, Tsung-YinTsung-YinTsaiWu, GangGangWuÓ Coileáin, CormacCormacÓ CoileáinZhao, Yan-FengYan-FengZhaoZhang, DuanDuanZhangHung, Kuan-MingKuan-MingHungCHING-RAY CHANGYUH-RENN WUWu, Han-ChunHan-ChunWu2022-04-252022-04-25202119448244https://www.scopus.com/inward/record.uri?eid=2-s2.0-85116580675&doi=10.1021%2facsami.1c11534&partnerID=40&md5=48a37c38537493fd336bef4309e50f67https://scholars.lib.ntu.edu.tw/handle/123456789/607377The fabrication of graphene/SnS2van der Waals photodetectors and their photoelectrical properties are systematically investigated. It was found that a dry transferred graphene/SnS2van der Waals heterostructure had a broadband sensing range from ultraviolet (365 nm) to near-infrared (2.24 μm) and respective improved responsivities and photodetectivities of 7.7 × 103A/W and 8.9 × 1013jones at 470 nm and 2 A/W and 1.8 × 1010jones at 1064 nm. Moreover, positive and negative photoconductance effects were observed when the photodetectors were illuminated by photon sources with energies greater and smaller than the bandgap of SnS2, respectively. The photoresponsivity (R) versus incident power density (P) follows the empirical lawR?Pinβ, with β > ?1 for positive photoconductance effects and β < ?1 for negative photoconductance effects. On the basis of the Fowler-Nordheim tunneling model and a Poisson and drift-diffusion simulation, we show quantitatively that the barrier height and barrier width of the heterostructure photodetector could be controlled by a laser and an external electrical field through a photogating effect generated by carriers trapped at the interface, which could be used to tune the separation and transport of photogenerated carriers. Our results may be useful for the design of high performance van der Waals heterojunction photodetectors. ? 2021 American Chemical Societybroadband photodetectorgraphenenegative photoconductance effectphotogating effectSnS2van der Waals heterostructureGrapheneInfrared devicesIV-VI semiconductorsPhotodetectorsPhotonsSemiconducting tin compoundsSulfur compoundsVan der Waals forces'Dry' [Broadband photodetectorNegative photoconductance effectPhoto-electrical propertiesPhotoconductancePhotogating effectPhotoresponsivitySensing rangesVan der WaalVan der waal heterostructureHeterojunctionsjournal article10.1021/acsami.1c11534345467152-s2.0-85116580675