title: Black phosphorus gas sensors.
abstract: The utilization of black phosphorus and its monolayer (phosphorene) and few-layers in field-effect transistors has attracted a lot of attention to this elemental two-dimensional material. Various studies on optimization of black phosphorus field-effect transistors, PN junctions, photodetectors, and other applications have been demonstrated. Although chemical sensing based on black phosphorus devices was theoretically predicted, there is still no experimental verification of such an important study of this material. In this article, we report on chemical sensing of nitrogen dioxide (NO2) using field-effect transistors based on multilayer black phosphorus. Black phosphorus sensors exhibited increased conduction upon NO2 exposure and excellent sensitivity for detection of NO2 down to 5 ppb. Moreover, when the multilayer black phosphorus field-effect transistor was exposed to NO2 concentrations of 5, 10, 20, and 40 ppb, its relative conduction change followed the Langmuir isotherm for molecules adsorbed on a surface. Additionally, on the basis of an exponential conductance change, the rate constants for adsorption and desorption of NO2 on black phosphorus were extracted for different NO2 concentrations, and they were in the range of 130-840 s. These results shed light on important electronic and sensing characteristics of black phosphorus, which can be utilized in future studies and applications.
authors.affiliation: †Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, United States.|‡Department of Electrical Engineering, University of Jeddah, Abdullah Sulayman Street, Jeddah 22254, Saudi Arabia.
authors.forename: Ahmad N
authors.initials: AN
authors.lastname: Abbas
authors.affiliation: †Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, United States.
authors.forename: Bilu
authors.initials: B
authors.lastname: Liu
authors.affiliation: †Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, United States.
authors.forename: Liang
authors.initials: L
authors.lastname: Chen
authors.affiliation: †Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, United States.
authors.forename: Yuqiang
authors.initials: Y
authors.lastname: Ma
authors.affiliation: †Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, United States.
authors.forename: Sen
authors.initials: S
authors.lastname: Cong
authors.affiliation: †Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, United States.
authors.forename: Noppadol
authors.initials: N
authors.lastname: Aroonyadet
authors.affiliation: §Department of Chemistry, Technische Universität München, Lichtenbergstraße 4, Garching b, München 485748, Germany.
authors.forename: Marianne
authors.initials: M
authors.lastname: Köpf
authors.affiliation: §Department of Chemistry, Technische Universität München, Lichtenbergstraße 4, Garching b, München 485748, Germany.
authors.forename: Tom
authors.initials: T
authors.lastname: Nilges
authors.affiliation: †Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, United States.
authors.forename: Chongwu
authors.initials: C
authors.lastname: Zhou
keywords: NO2; black phosphorus; charge transfer; chemical sensing; gas sensing; phosphorene