Air Stable Doping and Intrinsic Mobility Enhancement in Monolayer Molybdenum Disulfide by Amorphous Titanium Suboxide Encapsulation

Amritesh Rai, Amithraj Valsaraj, Hema C.P. Movva, Anupam Roy, Rudresh Ghosh, Sushant Sonde, Sangwoo Kang, Jiwon Chang, Tanuj Trivedi, Rik Dey, Samaresh Guchhait, Stefano Larentis, Leonard F. Register, Emanuel Tutuc, Sanjay K. Banerjee

Research output: Contribution to journalArticlepeer-review

116 Citations (Scopus)

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 cm2/V-s were realized using this doping technique. Moreover, intrinsic mobility as high as 102 cm2/V-s at 300 K and 501 cm2/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.

Original languageEnglish
Pages (from-to)4329-4336
Number of pages8
JournalNano letters
Volume15
Issue number7
DOIs
Publication statusPublished - 2015 Jul 8

Bibliographical note

Publisher Copyright:
© 2015 American Chemical Society.

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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