title: Black Phosphorus Mid-Infrared Photodetectors with High Gain.
abstract: Recently, black phosphorus (BP) has joined the two-dimensional material family as a promising candidate for photonic applications due to its moderate bandgap, high carrier mobility, and compatibility with a diverse range of substrates. Photodetectors are probably the most explored BP photonic devices, however, their unique potential compared with other layered materials in the mid-infrared wavelength range has not been revealed. Here, we demonstrate BP mid-infrared detectors at 3.39 μm with high internal gain, resulting in an external responsivity of 82 A/W. Noise measurements show that such BP photodetectors are capable of sensing mid-infrared light in the picowatt range. Moreover, the high photoresponse remains effective at kilohertz modulation frequencies, because of the fast carrier dynamics arising from BP's moderate bandgap. The high photoresponse at mid-infrared wavelengths and the large dynamic bandwidth, together with its unique polarization dependent response induced by low crystalline symmetry, can be coalesced to promise photonic applications such as chip-scale mid-infrared sensing and imaging at low light levels.
authors.affiliation: Department of Electrical Engineering, Yale University , New Haven, Connecticut 06511, United States.
authors.forename: Qiushi
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Vienna University of Technology, Institute of Photonics , Gußhausstraße 27-29, 1040 Vienna, Austria.
authors.forename: Andreas
authors.initials: A
authors.lastname: Pospischil
authors.affiliation: Department of Electrical Engineering, Yale University , New Haven, Connecticut 06511, United States.
authors.forename: Maruf
authors.initials: M
authors.lastname: Bhuiyan
authors.affiliation: Department of Electrical and Computer Engineering, University of Massachusetts , Amherst, Massachusetts 01003, United States.
authors.forename: Hao
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Ming Hsieh Department of Electrical Engineering, University of Southern California , Los Angeles, California 90089, United States.
authors.forename: He
authors.initials: H
authors.lastname: Tian
authors.affiliation: IBM Thomas J. Watson Research Center , Yorktown Heights, New York 10598, United States.
authors.forename: Damon
authors.initials: D
authors.lastname: Farmer
authors.affiliation: Department of Electrical Engineering, Yale University , New Haven, Connecticut 06511, United States.
authors.forename: Bingchen
authors.initials: B
authors.lastname: Deng
authors.affiliation: Department of Electrical Engineering, Yale University , New Haven, Connecticut 06511, United States.
authors.forename: Cheng
authors.initials: C
authors.lastname: Li
authors.affiliation: IBM Thomas J. Watson Research Center , Yorktown Heights, New York 10598, United States.
authors.forename: Shu-Jen
authors.initials: SJ
authors.lastname: Han
authors.affiliation: Ming Hsieh Department of Electrical Engineering, University of Southern California , Los Angeles, California 90089, United States.
authors.forename: Han
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Electrical and Computer Engineering, University of Massachusetts , Amherst, Massachusetts 01003, United States.
authors.forename: Qiangfei
authors.initials: Q
authors.lastname: Xia
authors.affiliation: Department of Electrical Engineering, Yale University , New Haven, Connecticut 06511, United States.
authors.forename: Tso-Ping
authors.initials: TP
authors.lastname: Ma
authors.affiliation: Vienna University of Technology, Institute of Photonics , Gußhausstraße 27-29, 1040 Vienna, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Mueller
authors.affiliation: Department of Electrical Engineering, Yale University , New Haven, Connecticut 06511, United States.
authors.forename: Fengnian
authors.initials: F
authors.lastname: Xia
keywords: Black phosphorus; mid-IR photodetectors; photoconductive gain; photogating effect