title: Air Stable Doping and Intrinsic Mobility Enhancement in Monolayer Molybdenum Disulfide by Amorphous Titanium Suboxide Encapsulation.
abstract: To reduce Schottky-barrier-induced contact and access resistance, and the impact of charged impurity and phonon scattering on mobility in devices based on 2D transition metal dichalcogenides (TMDs), considerable effort has been put into exploring various doping techniques and dielectric engineering using high-κ oxides, respectively. The goal of this work is to demonstrate a high-κ dielectric that serves as an effective n-type charge transfer dopant on monolayer (ML) molybdenum disulfide (MoS2). Utilizing amorphous titanium suboxide (ATO) as the "high-κ dopant", we achieved a contact resistance of ∼180 Ω·μm that is the lowest reported value for ML MoS2. An ON current as high as 240 μA/μm and field effect mobility as high as 83 cm(2)/V-s were realized using this doping technique. Moreover, intrinsic mobility as high as 102 cm(2)/V-s at 300 K and 501 cm(2)/V-s at 77 K were achieved after ATO encapsulation that are among the highest mobility values reported on ML MoS2. We also analyzed the doping effect of ATO films on ML MoS2, a phenomenon that is absent when stoichiometric TiO2 is used, using ab initio density functional theory (DFT) calculations that shows excellent agreement with our experimental findings. On the basis of the interfacial-oxygen-vacancy mediated doping as seen in the case of high-κ ATO-ML MoS2, we propose a mechanism for the mobility enhancement effect observed in TMD-based devices after encapsulation in a high-κ dielectric environment.
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Amritesh
authors.initials: A
authors.lastname: Rai
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Amithraj
authors.initials: A
authors.lastname: Valsaraj
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Hema C P
authors.initials: HC
authors.lastname: Movva
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Anupam
authors.initials: A
authors.lastname: Roy
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Rudresh
authors.initials: R
authors.lastname: Ghosh
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Sushant
authors.initials: S
authors.lastname: Sonde
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Sangwoo
authors.initials: S
authors.lastname: Kang
authors.affiliation: ‡SEMATECH, 257 Fuller Rd #2200, Albany, New York-12203, United States.
authors.forename: Jiwon
authors.initials: J
authors.lastname: Chang
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Tanuj
authors.initials: T
authors.lastname: Trivedi
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Rik
authors.initials: R
authors.lastname: Dey
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Samaresh
authors.initials: S
authors.lastname: Guchhait
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Stefano
authors.initials: S
authors.lastname: Larentis
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Leonard F
authors.initials: LF
authors.lastname: Register
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Tutuc
authors.affiliation: †Microelectronics Research Center and Department of Electrical and Computer Engineering, The University of Texas at Austin, Austin, Texas 78758, United States.
authors.forename: Sanjay K
authors.initials: SK
authors.lastname: Banerjee
keywords: Molybdenum disulfide (MoS2); Schottky barrier; amorphous titanium suboxide (ATO); contact resistance; doping; field effect transistor; high-κ dielectric; intrinsic mobility