Tuning on-off current ratio and field-effect mobility in a MoS 2-graphene heterostructure via schottky barrier modulation

Chih Jen Shih, Qing Hua Wang, Youngwoo Son, Zhong Jin, Daniel Blankschtein, Michael S. Strano

Research output: Contribution to journalArticle

162 Scopus citations

Abstract

Field-effect transistor (FET) devices composed of a MoS2- graphene heterostructure can combine the advantages of high carrier mobility in graphene with the permanent band gap of MoS2 for digital applications. Herein, we investigate the electron transfer, photoluminescence, and gate-controlled carrier transport in such a heterostructure. We show that the junction is a Schottky barrier, whose height can be artificially controlled by gating or doping graphene. When the applied gate voltage (or the doping level) is zero, the photoexcited electron-hole pairs in monolayer MoS 2 can be split by the heterojunction, significantly reducing the photoluminescence. By applying negative gate voltage (or p-doping) in graphene, the interlayer impedance formed between MoS2 and graphene exhibits an 100-fold increase. For the first time, we show that the gate-controlled interlayer Schottky impedance can be utilized to modulate carrier transport in graphene, significantly depleting the hole transport, but preserving the electron transport. Accordingly, we demonstrate a new type of FET device, which enables a controllable transition from NMOS digital to bipolar characteristics. In the NMOS digital regime, we report a very high room temperature on/off current ratio (ION/IOFF ∼ 36) in comparison to graphene-based FET devices without sacrificing the field-effect electron mobilities in graphene. By engineering the source/drain contact area, we further estimate that a higher value of ION/IOFF up to 100 can be obtained in the device architecture considered. The device architecture presented here may enable semiconducting behavior in graphene for digital and analogue electronics.

Original languageEnglish (US)
Pages (from-to)5790-5798
Number of pages9
JournalACS nano
Volume8
Issue number6
DOIs
StatePublished - Jun 24 2014

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Keywords

  • Schottky barrier modulation
  • field-effect mobility
  • field-effect transistor devices

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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