title: Bandgap Engineering of Phosphorene by Laser Oxidation toward Functional 2D Materials.
abstract: We demonstrate a straightforward and effective laser pruning approach to reduce multilayer black phosphorus (BP) to few-layer BP under ambient condition. Phosphorene oxides and suboxides are formed and the degree of laser-induced oxidation is controlled by the laser power. Since the band gaps of the phosphorene suboxide depend on the oxygen concentration, this simple technique is able to realize localized band gap engineering of the thin BP. Micropatterns of few-layer phosphorene suboxide flakes with unique optical and fluorescence properties are created. Remarkably, some of these suboxide flakes display long-term (up to 2 weeks) stability in ambient condition. Comparing against the optical properties predicted by first-principle calculations, we develop a "calibration" map in using focused laser power as a handle to tune the band gap of the BP suboxide flake. Moreover, the surface of the laser patterned region is altered to be sensitive to toxic gas by way of fluorescence contrast. Therefore, the multicolored display is further demonstrated as a toxic gas monitor. In addition, the BP suboxide flake is demonstrated to exhibit higher drain current modulation and mobility comparable to that of the pristine BP in the electronic application.
authors.affiliation: Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore.
authors.forename: Junpeng
authors.initials: J
authors.lastname: Lu
authors.affiliation: Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore.
authors.forename: Jing
authors.initials: J
authors.lastname: Wu
authors.affiliation: Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Carvalho
authors.affiliation: Department of Chemistry, Boston University , 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States.
authors.forename: Angelo
authors.initials: A
authors.lastname: Ziletti
authors.affiliation: Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) , 3 Research Link, Singapore 117602, Singapore.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Liu
authors.affiliation: Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore.
authors.forename: Junyou
authors.initials: J
authors.lastname: Tan
authors.affiliation: Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research) , 3 Research Link, Singapore 117602, Singapore.
authors.forename: Yifan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore.|Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore.
authors.forename: A H
authors.initials: AH
authors.lastname: Castro Neto
authors.affiliation: Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore.|Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore.
authors.forename: Barbaros
authors.initials: B
authors.lastname: Özyilmaz
authors.affiliation: Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117542, Singapore.|Center For Advanced 2D Materials and Graphene Research Center, National University of Singapore , 6 Science Drive 2, Singapore 117546, Singapore.
authors.forename: Chorng Haur
authors.initials: CH
authors.lastname: Sow
keywords: 2D material; laser; localized oxidation; phosphorene; photonics