title: Probing Out-of-Plane Charge Transport in Black Phosphorus with Graphene-Contacted Vertical Field-Effect Transistors.
abstract: Black phosphorus (BP) has recently emerged as a promising narrow band gap layered semiconductor with optoelectronic properties that bridge the gap between semimetallic graphene and wide band gap transition metal dichalcogenides such as MoS2. To date, BP field-effect transistors have utilized a lateral geometry with in-plane transport dominating device characteristics. In contrast, we present here a vertical field-effect transistor geometry based on a graphene/BP van der Waals heterostructure. The resulting device characteristics include high on-state current densities (>1600 A/cm(2)) and current on/off ratios exceeding 800 at low temperature. Two distinct charge transport mechanisms are identified, which are dominant for different regimes of temperature and gate voltage. In particular, the Schottky barrier between graphene and BP determines charge transport at high temperatures and positive gate voltages, whereas tunneling dominates at low temperatures and negative gate voltages. These results elucidate out-of-plane electronic transport in BP and thus have implications for the design and operation of BP-based van der Waals heterostructures.
authors.affiliation: Department of Materials Science and Engineering, ⊥Department of Chemistry, and #Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States.|SKKU Advanced Institute of Nanotechnology (SAINT), §School of Chemical Engineering, and ∥Department of Physics, Sungkyunkwan University , Suwon 440-746, Republic of Korea.
authors.forename: Junmo
authors.initials: J
authors.lastname: Kang
authors.affiliation: Department of Materials Science and Engineering, ⊥Department of Chemistry, and #Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States.|SKKU Advanced Institute of Nanotechnology (SAINT), §School of Chemical Engineering, and ∥Department of Physics, Sungkyunkwan University , Suwon 440-746, Republic of Korea.
authors.forename: Deep
authors.initials: D
authors.lastname: Jariwala
authors.affiliation: Department of Materials Science and Engineering, ⊥Department of Chemistry, and #Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States.|SKKU Advanced Institute of Nanotechnology (SAINT), §School of Chemical Engineering, and ∥Department of Physics, Sungkyunkwan University , Suwon 440-746, Republic of Korea.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Ryder
authors.affiliation: Department of Materials Science and Engineering, ⊥Department of Chemistry, and #Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States.|SKKU Advanced Institute of Nanotechnology (SAINT), §School of Chemical Engineering, and ∥Department of Physics, Sungkyunkwan University , Suwon 440-746, Republic of Korea.
authors.forename: Spencer A
authors.initials: SA
authors.lastname: Wells
authors.affiliation: Department of Materials Science and Engineering, ⊥Department of Chemistry, and #Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States.|SKKU Advanced Institute of Nanotechnology (SAINT), §School of Chemical Engineering, and ∥Department of Physics, Sungkyunkwan University , Suwon 440-746, Republic of Korea.
authors.forename: Yongsuk
authors.initials: Y
authors.lastname: Choi
authors.affiliation: Department of Materials Science and Engineering, ⊥Department of Chemistry, and #Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States.|SKKU Advanced Institute of Nanotechnology (SAINT), §School of Chemical Engineering, and ∥Department of Physics, Sungkyunkwan University , Suwon 440-746, Republic of Korea.
authors.forename: Euyheon
authors.initials: E
authors.lastname: Hwang
authors.affiliation: Department of Materials Science and Engineering, ⊥Department of Chemistry, and #Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States.|SKKU Advanced Institute of Nanotechnology (SAINT), §School of Chemical Engineering, and ∥Department of Physics, Sungkyunkwan University , Suwon 440-746, Republic of Korea.
authors.forename: Jeong Ho
authors.initials: JH
authors.lastname: Cho
authors.affiliation: Department of Materials Science and Engineering, ⊥Department of Chemistry, and #Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States.|SKKU Advanced Institute of Nanotechnology (SAINT), §School of Chemical Engineering, and ∥Department of Physics, Sungkyunkwan University , Suwon 440-746, Republic of Korea.
authors.forename: Tobin J
authors.initials: TJ
authors.lastname: Marks
authors.affiliation: Department of Materials Science and Engineering, ⊥Department of Chemistry, and #Department of Electrical Engineering and Computer Science, Northwestern University , Evanston, Illinois 60208, United States.|SKKU Advanced Institute of Nanotechnology (SAINT), §School of Chemical Engineering, and ∥Department of Physics, Sungkyunkwan University , Suwon 440-746, Republic of Korea.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Hersam
mesh_terms: D006108:Graphite; D013440:Sulfides; D014173:Transistors, Electronic; D028561:Transition Elements
chemical_list: D013440:Sulfides; D028561:Transition Elements; D006108:Graphite
keywords: Phosphorene; Schottky barrier; heterostructure; short channel; van der Waals