title: High photosensitivity and broad spectral response of multi-layered germanium sulfide transistors.
abstract: In this paper, we report the optoelectronic properties of multi-layered GeS nanosheet (∼28 nm thick)-based field-effect transistors (called GeS-FETs). The multi-layered GeS-FETs exhibit remarkably high photoresponsivity of Rλ ∼ 206 A W(-1) under 1.5 μW cm(-2) illumination at λ = 633 nm, Vg = 0 V, and Vds = 10 V. The obtained Rλ ∼ 206 A W(-1) is excellent as compared with a GeS nanoribbon-based and the other family members of group IV-VI-based photodetectors in the layered-materials realm, such as GeSe and SnS2. The gate-dependent photoresponsivity of GeS-FETs was further measured to be able to reach Rλ ∼ 655 A W(-1) operated at Vg = -80 V. Moreover, the multi-layered GeS photodetector holds high external quantum efficiency (EQE ∼ 4.0 × 10(4)%) and specific detectivity (D* ∼ 2.35 × 10(13) Jones). The measured D* is comparable to those of the advanced commercial Si- and InGaAs-based photodiodes. The GeS photodetector also shows an excellent long-term photoswitching stability over a long period of operation (>1 h). These extraordinary properties of high photocurrent generation, broad spectral range, and long-term stability make the GeS-FET photodetector a highly qualified candidate for future optoelectronic applications.
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan. ytcchem@ntu.edu.tw and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
authors.forename: Rajesh Kumar
authors.initials: RK
authors.lastname: Ulaganathan
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan. ytcchem@ntu.edu.tw and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
authors.forename: Yi-Ying
authors.initials: YY
authors.lastname: Lu
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan. ytcchem@ntu.edu.tw and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
authors.forename: Chia-Jung
authors.initials: CJ
authors.lastname: Kuo
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan and Nano Science and Technology Program and Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Nankang 11529, Taiwan.
authors.forename: Srinivasa Reddy
authors.initials: SR
authors.lastname: Tamalampudi
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Raman
authors.initials: R
authors.lastname: Sankar
authors.affiliation: Nano Science and Technology Program and Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Nankang 11529, Taiwan and Department of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Karunakara Moorthy
authors.initials: KM
authors.lastname: Boopathi
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan and Nano Science and Technology Program and Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Nankang 11529, Taiwan.
authors.forename: Ankur
authors.initials: A
authors.lastname: Anand
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan. ytcchem@ntu.edu.tw and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
authors.forename: Kanchan
authors.initials: K
authors.lastname: Yadav
authors.affiliation: Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan and Nano Science and Technology Program and Molecular Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Nankang 11529, Taiwan.
authors.forename: Roshan Jesus
authors.initials: RJ
authors.lastname: Mathew
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan. ytcchem@ntu.edu.tw and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
authors.forename: Chia-Rung
authors.initials: CR
authors.lastname: Liu
authors.affiliation: Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan.
authors.forename: Fang Cheng
authors.initials: FC
authors.lastname: Chou
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan. ytcchem@ntu.edu.tw and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan.
authors.forename: Yit-Tsong
authors.initials: YT
authors.lastname: Chen