Optimized photoelectric performance of MoS2/graphene heterostructure device induced by swift heavy ion irradiation

Two-dimensional materials with exceptional electronic and photoelectric properties are expected to develop a new-generation of ultrathin, high efficiency, broadband, and flexible photodetectors. For the potential application towards outer space exploration, the harsh irradiation environment must be taken into consideration. In this work, irradiation effects of MoS2/Graphene heterostructure field effect transistors (MoS2/G FETs) induced by swift heavy ions (SHIs) were explored. After irradiation, a new Raman peak denoted as D peak emerged, which demonstrated that SHI irradiation induced damage in graphene. Photoluminescence investigation of MoS2 indicated that SHI irradiation activated the excitation conversion of trion A- to excitation A0. Latent tracks were observed on MoS2/G/SiO2 by using atomic force microscope. The decreased resistance and increased carrier mobilities were detected at fluence lower than 5 x 1010 ions/cm2, which could be ascribed to the localized annealing of graphene during irradiation. The increased photocurrent and responsivity at fluence lower than 1 x 1010 ions/cm2 could be interpreted as the enhanced photoinduced gate voltage resulting from the SHI irradiation induced defects in MoS2/G FET. The devices were deteriorated at fluence of 1 x 1011 ions/cm2. The optimized and degraded properties of the devices could be ascribed to competition among doping, local annealing and defect scattering.