title: Colossal Ultraviolet Photoresponsivity of Few-Layer Black Phosphorus.
abstract: Black phosphorus has an orthorhombic layered structure with a layer-dependent direct band gap from monolayer to bulk, making this material an emerging material for photodetection. Inspired by this and the recent excitement over this material, we studied the optoelectronics characteristics of high-quality, few-layer black phosphorus-based photodetectors over a wide spectrum ranging from near-ultraviolet (UV) to near-infrared (NIR). It is demonstrated for the first time that black phosphorus can be configured as an excellent UV photodetector with a specific detectivity ∼3 × 10(13) Jones. More critically, we found that the UV photoresponsivity can be significantly enhanced to ∼9 × 10(4) A W(-1) by applying a source-drain bias (VSD) of 3 V, which is the highest ever measured in any 2D material and 10(7) times higher than the previously reported value for black phosphorus. We attribute such a colossal UV photoresponsivity to the resonant-interband transition between two specially nested valence and conduction bands. These nested bands provide an unusually high density of states for highly efficient UV absorption due to the singularity of their nature.
authors.affiliation: NanoCore, National University of Singapore , 117576, Singapore.
authors.forename: Jing
authors.initials: J
authors.lastname: Wu
authors.affiliation: NanoCore, National University of Singapore , 117576, Singapore.
authors.forename: Gavin Kok Wai
authors.initials: GK
authors.lastname: Koon
authors.forename: Du
authors.initials: D
authors.lastname: Xiang
authors.forename: Cheng
authors.initials: C
authors.lastname: Han
authors.forename: Chee Tat
authors.initials: CT
authors.lastname: Toh
authors.forename: Eeshan S
authors.initials: ES
authors.lastname: Kulkarni
authors.forename: Ivan
authors.initials: I
authors.lastname: Verzhbitskiy
authors.forename: Alexandra
authors.initials: A
authors.lastname: Carvalho
authors.forename: Aleksandr S
authors.initials: AS
authors.lastname: Rodin
authors.forename: Steven P
authors.initials: SP
authors.lastname: Koenig
authors.forename: Goki
authors.initials: G
authors.lastname: Eda
authors.affiliation: National University of Singapore (Suzhou) Research Institute , 377 Lin Quan Street, Suzhou Industrial Park, Jiang Su 215123, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: A H Castro
authors.initials: AH
authors.lastname: Neto
authors.affiliation: NanoCore, National University of Singapore , 117576, Singapore.
authors.forename: Barbaros
authors.initials: B
authors.lastname: Özyilmaz
keywords: black phosphorus; direct band gap; optoelectronics; phototransistor; ultraviolet