MoTe2 Lateral Homojunction Field-Effect Transistors Fabricated using Flux-Controlled Phase Engineering

Rui Ma, Huairuo Zhang, Youngdong Yoo, Zachary Patrick Degregorio, Lun Jin, Prafful Golani, Javad Ghasemi Azadani, Tony Low, James Johns, Leonid A. Bendersky, Albert V. Davydov, Steven J Koester

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

The coexistence of metallic and semiconducting polymorphs in transition-metal dichalcogenides (TMDCs) can be utilized to solve the large contact resistance issue in TMDC-based field effect transistors (FETs). A semiconducting hexagonal (2H) molybdenum ditelluride (MoTe2) phase, metallic monoclinic (1T′) MoTe2 phase, and their lateral homojunctions can be selectively synthesized in situ by chemical vapor deposition due to the small free energy difference between the two phases. Here, we have investigated, in detail, the structural and electrical properties of in situ-grown lateral 2H/1T′ MoTe2 homojunctions grown using flux-controlled phase engineering. Using atomic-resolution plan-view and cross-sectional transmission electron microscopy analyses, we show that the round regions of near-single-crystalline 2H-MoTe2 grow out of a polycrystalline 1T′-MoTe2 matrix. We further demonstrate the operation of MoTe2 FETs made on these in situ-grown lateral homojunctions with 1T′ contacts. The use of a 1T′ phase as electrodes in MoTe2 FETs effectively improves the device performance by substantially decreasing the contact resistance. The contact resistance of 1T′ electrodes extracted from transfer length method measurements is 470 ± 30 ω·μm. Temperature- and gate-voltage-dependent transport characteristics reveal a flat-band barrier height of 30 ± 10 meV at the lateral 2H/1T′ interface that is several times smaller and shows a stronger gate modulation, compared to the metal/2H Schottky barrier height. The information learned from this analysis will be critical to understanding the properties of MoTe2 homojunction FETs for use in memory and logic circuity applications.

Original languageEnglish (US)
Pages (from-to)8035-8046
Number of pages12
JournalACS nano
Volume13
Issue number7
DOIs
StatePublished - Jul 23 2019

Bibliographical note

Funding Information:
S.J.K. and R.M. were supported by the Defense Threat Reduction Agency Basic Research through award no. HDTRA1-14-1-0042 and partially by the National Science Foundation (NSF) through the University of Minnesota MRSEC under award no. DMR-1420013. J.G.A. and T.L. were supported by the NSF through award no. ECCS-1542202. Parts of this work were carried out in the Characterization Facility University of Minnesota, which has received capital equipment funding from the NSF through the MRSEC program under award no. DMR-1420013. Portions of this work were also conducted in the Minnesota Nano Center which is supported by the NSF through the National Nanotechnology Coordinated Infrastructure (NNCI) under award no. ECCS-1542202. We acknowledge computational support from the Minnesota Supercomputing Institute (MSI). The TEM characterization was carried out by H.Z. L.A.B., and A.V.D. at the National Institute of Standards and Technology (NIST). A.V.D. acknowledges the support of Material Genome Initiative funding allocated to NIST. H.Z. acknowledges support from the U.S. Department of Commerce, NIST under the financial assistance award no. 70NANB17H249. Y.Y. was supported by the NRF grants funded by the MSIT (award nos. 2018R1C1B5044670 and 2019R1C1C1008070). P. G. was supported by the NSF through award no. ECCS-1708769

Funding Information:
S.J.K. and R.M. were supported by the Defense Threat Reduction Agency Basic Research through award no. HDTRA1-14-1-0042 and partially by the National Science Foundation (NSF) through the University of Minnesota MRSEC under award no. DMR-1420013. J.G.A. and T.L. were supported by the NSF through award no. ECCS-1542202. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which has received capital equipment funding from the NSF through the MRSEC program under award no. DMR-1420013. Portions of this work were also conducted in the Minnesota Nano Center, which is supported by the NSF through the National Nanotechnology Coordinated Infrastructure (NNCI) under award no. ECCS-1542202. We acknowledge computational support from the Minnesota Supercomputing Institute (MSI). The TEM characterization was carried out by H.Z., L.A.B., and A.V.D. at the National Institute of Standards and Technology (NIST). A.V.D. acknowledges the support of Material Genome Initiative funding allocated to NIST. H.Z. acknowledges support from the U.S. Department of Commerce, NIST under the financial assistance award no. 70NANB17H249. Y.Y. was supported by the NRF grants funded by the MSIT (award nos. 2018R1C1B5044670 and 2019R1C1C1008070). P. G. was supported by the NSF through award no. ECCS-1708769.

Publisher Copyright:
© Copyright 2019 American Chemical Society.

Keywords

  • chemical vapor deposition
  • lateral homojunction
  • MoTe
  • phase engineering
  • Schottky barrier height
  • transition-metal dichalcogenide

How much support was provided by MRSEC?

  • Partial

Reporting period for MRSEC

  • Period 6

PubMed: MeSH publication types

  • Journal Article

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