title: Electrical and Thermoelectric Transport by Variable Range Hopping in Thin Black Phosphorus Devices.
abstract: The moderate band gap of black phosphorus (BP) in the range of 0.3-2 eV, along a high mobility of a few hundred cm(2) V(-1) s(-1) provides a bridge between the gapless graphene and relatively low-mobility transition metal dichalcogenides. Here, we study the mechanism of electrical and thermoelectric transport in 10-30 nm thick BP devices by measurements of electrical conductance and thermopower (S) with various temperatures (T) and gate-electric fields. The T dependences of S and the sheet conductance (σ□) of the BP devices show behaviors of T(1/3) and exp[-(1/T)(1/3)], respectively, where S reaches ∼0.4 mV/K near room T. This result indicates that two-dimensional (2D) Mott's variable range hopping (VRH) is a dominant mechanism in the thermoelectric and electrical transport in our examined thin BP devices. We consider the origin of the 2D Mott's VRH transport in our BPs as trapped charges at the surface of the underlying SiO2 based on the analysis with observed multiple quantum dots.
authors.affiliation: Korea Research Institute of Standards and Science , Daejeon 34113, Republic of Korea.|Department of Physics, Chungnam National University , Daejeon 34134, Republic of Korea.
authors.forename: Seon Jae
authors.initials: SJ
authors.lastname: Choi
authors.affiliation: Korea Research Institute of Standards and Science , Daejeon 34113, Republic of Korea.|Department of Physics, Chonbuk National University , Jeonju 54896, Republic of Korea.
authors.forename: Bum-Kyu
authors.initials: BK
authors.lastname: Kim
authors.affiliation: Korea Research Institute of Standards and Science , Daejeon 34113, Republic of Korea.|Department of Physics, Chungbuk National University , Cheongju 28644, Republic of Korea.
authors.forename: Tae-Ho
authors.initials: TH
authors.lastname: Lee
authors.affiliation: Korea Research Institute of Chemical Technology , Daejeon 34114, Republic of Korea.
authors.forename: Yun Ho
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Zuanyi
authors.initials: Z
authors.lastname: Li
authors.affiliation: Electrical Engineering, Stanford University , Stanford, California 94305, United States.
authors.forename: Eric
authors.initials: E
authors.lastname: Pop
authors.affiliation: Department of Physics, Chonbuk National University , Jeonju 54896, Republic of Korea.
authors.forename: Ju-Jin
authors.initials: JJ
authors.lastname: Kim
authors.affiliation: Department of Physics, Chungnam National University , Daejeon 34134, Republic of Korea.
authors.forename: Jong Hyun
authors.initials: JH
authors.lastname: Song
authors.affiliation: Korea Research Institute of Standards and Science , Daejeon 34113, Republic of Korea.|Department of Nano Science, University of Science and Technology , Daejeon 34113, Republic of Korea.
authors.forename: Myung-Ho
authors.initials: MH
authors.lastname: Bae
keywords: black phosphorus; electrical conductance; thermopower; variable range hopping