title: A high performance, visible to mid-infrared photodetector based on graphene nanoribbons passivated with HfO2.
abstract: Graphene has drawn tremendous attention as a promising candidate for electronic and optoelectronic applications owing to its extraordinary properties, such as broadband absorption and ultrahigh mobility. Nevertheless, the absence of a bandgap makes graphene unfavorable for digital electronic or photonic applications. Although patterning graphene into nanostructures with the quantum confinement effect is able to open a bandgap, devices based on these graphene nanostructures generally suffer from low carrier mobility and scattering losses. In this paper, we demonstrated that encapsulation of an atomic layer deposited high-quality HfO2 film will greatly enhance the carrier mobility and decrease the scattering losses of graphene nanoribbons, because this high-k dielectric layer weakens carrier coulombic interactions. In addition, a photodetector based on HfO2 layer capped graphene nanoribbons can cover broadband wavelengths from visible to mid-infrared at room temperature, exhibiting ∼10 times higher responsivity than the one without a HfO2 layer in the visible regime and ∼8 times higher responsivity in the mid-infrared regime. The method employed here could be potentially used as a general approach to improve the performance of graphene nanostructures for electronic and optoelectronic applications.
authors.affiliation: Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore.
authors.forename: Xuechao
authors.initials: X
authors.lastname: Yu
authors.affiliation: Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, #08-03 Innovis, 138634, Singapore.
authors.forename: Zhaogang
authors.initials: Z
authors.lastname: Dong
authors.affiliation: Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore.
authors.forename: Tao
authors.initials: T
authors.lastname: Liu
authors.affiliation: Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore.
authors.forename: Jin
authors.initials: J
authors.lastname: Tao
authors.affiliation: Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore.
authors.forename: Yongquan
authors.initials: Y
authors.lastname: Zeng
authors.affiliation: Singapore University of Technology and Design, 8 Somapah Road, 487372, Singapore and Institute of Materials Research and Engineering, Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, #08-03 Innovis, 138634, Singapore.
authors.forename: Joel K W
authors.initials: JK
authors.lastname: Yang
authors.affiliation: Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Nanyang Technological University, 639798, Singapore and Centre for Disruptive Photonics Technologies, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore. qjwang@ntu.edu.sg.
authors.forename: Qi Jie
authors.initials: QJ
authors.lastname: Wang