title: High Photoresponsivity and Short Photoresponse Times in Few-Layered WSe2 Transistors.
abstract: Here, we report the photoconducting response of field-effect transistors based on three atomic layers of chemical vapor transport grown WSe2 crystals mechanically exfoliated onto SiO2. We find that trilayered WSe2 field-effect transistors, built with the simplest possible architecture, can display high hole mobilities ranging from 350 cm(2)/(V s) at room temperature (saturating at a value of ∼500 cm(2)/(V s) below 50 K) displaying a strong photocurrent response, which leads to exceptionally high photoresponsivities up to 7 A/W under white light illumination of the entire channel for power densities p < 10(2) W/m(2). Under a fixed wavelength of λ = 532 nm and a laser spot size smaller than the conducting channel area, we extract photoresponsitivities approaching 100 mA/W with concomitantly high external quantum efficiencies up to ∼40% at room temperature. These values surpass values recently reported from more complex architectures, such as graphene and transition metal dichalcogenides based heterostructures. Also, trilayered WSe2 phototransistors display photoresponse times on the order of 10 μs. Our results indicate that the addition of a few atomic layers considerably decreases the photoresponse times, probably by minimizing the interaction with the substrates, while maintaining a very high photoresponsivity.
authors.affiliation: †National High Magnetic Field Lab, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States.
authors.forename: Nihar R
authors.initials: NR
authors.lastname: Pradhan
authors.affiliation: †National High Magnetic Field Lab, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States.|‡Department of Physics, Florida State University, Tallahassee, Florida 32306, United States.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Ludwig
authors.affiliation: †National High Magnetic Field Lab, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States.|‡Department of Physics, Florida State University, Tallahassee, Florida 32306, United States.
authors.forename: Zhengguang
authors.initials: Z
authors.lastname: Lu
authors.affiliation: †National High Magnetic Field Lab, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States.|‡Department of Physics, Florida State University, Tallahassee, Florida 32306, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rhodes
authors.affiliation: †National High Magnetic Field Lab, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Bishop
authors.affiliation: †National High Magnetic Field Lab, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States.
authors.forename: Komalavalli
authors.initials: K
authors.lastname: Thirunavukkuarasu
authors.affiliation: †National High Magnetic Field Lab, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: McGill
authors.affiliation: †National High Magnetic Field Lab, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Smirnov
authors.affiliation: †National High Magnetic Field Lab, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States.|‡Department of Physics, Florida State University, Tallahassee, Florida 32306, United States.
authors.forename: Luis
authors.initials: L
authors.lastname: Balicas
keywords: field-effect transistors; photocurrent; quantum efficiency; transition metal dichalcogenides; tungsten diselenide; two-dimensional atomic layers