title: High-performance n-type black phosphorus transistors with type control via thickness and contact-metal engineering.
abstract: Recent work has demonstrated excellent p-type field-effect switching in exfoliated black phosphorus, but type control has remained elusive. Here, we report unipolar n-type black phosphorus transistors with switching polarity control via contact-metal engineering and flake thickness, combined with oxygen and moisture-free fabrication. With aluminium contacts to black phosphorus, a unipolar to ambipolar transition occurs as flake thickness increases from 3 to 13 nm. The 13-nm aluminium-contacted flake displays graphene-like symmetric hole and electron mobilities up to 950 cm(2) V(-1) s(-1) at 300 K, while a 3 nm flake displays unipolar n-type switching with on/off ratios greater than 10(5) (10(7)) and electron mobility of 275 (630) cm(2) V(-1) s(-1) at 300 K (80 K). For palladium contacts, p-type behaviour dominates in thick flakes, while 2.5-7 nm flakes have symmetric ambipolar transport. These results demonstrate a leap in n-type performance and exemplify the logical switching capabilities of black phosphorus.
authors.affiliation: IBS Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: David J
authors.initials: DJ
authors.lastname: Perello
authors.affiliation: IBS Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: Sang Hoon
authors.initials: SH
authors.lastname: Chae
authors.affiliation: IBS Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: Seunghyun
authors.initials: S
authors.lastname: Song
authors.affiliation: 1] IBS Center for Integrated Nanostructure Physics, Institute for Basic Science, Sungkyunkwan University, Suwon 440-746, Korea [2] Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Korea [3] Department of Physics, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: Young Hee
authors.identifier: 0000000174038157
authors.initials: YH
authors.lastname: Lee