A Study of Vertical Transport through Graphene toward Control of Quantum Tunneling

Xiaodan Zhu, Sidong Lei, Shin Hung Tsai, Xiang Zhang, Jun Liu, Gen Yin, Min Tang, Carlos M. Torres, Aryan Navabi, Zehua Jin, Shiao Po Tsai, Hussam Qasem, Yong Wang, Robert Vajtai, Roger K. Lake, Pulickel M. Ajayan, Kang L. Wang

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

Vertical integration of van der Waals (vdW) materials with atomic precision is an intriguing possibility brought forward by these two-dimensional (2D) materials. Essential to the design and analysis of these structures is a fundamental understanding of the vertical transport of charge carriers into and across vdW materials, yet little has been done in this area. In this report, we explore the important roles of single layer graphene in the vertical tunneling process as a tunneling barrier. Although a semimetal in the lateral lattice plane, graphene together with the vdW gap act as a tunneling barrier that is nearly transparent to the vertically tunneling electrons due to its atomic thickness and the transverse momenta mismatch between the injected electrons and the graphene band structure. This is accentuated using electron tunneling spectroscopy (ETS) showing a lack of features corresponding to the Dirac cone band structure. Meanwhile, the graphene acts as a lateral conductor through which the potential and charge distribution across the tunneling barrier can be tuned. These unique properties make graphene an excellent 2D atomic grid, transparent to charge carriers, and yet can control the carrier flux via the electrical potential. A new model on the quantum capacitance's effect on vertical tunneling is developed to further elucidate the role of graphene in modulating the tunneling process. This work may serve as a general guideline for the design and analysis of vdW vertical tunneling devices and heterostructures, as well as the study of electron/spin injection through and into vdW materials.

Original languageEnglish
Pages (from-to)682-688
Number of pages7
JournalNano letters
Volume18
Issue number2
DOIs
Publication statusPublished - 2018 Feb 14

All Science Journal Classification (ASJC) codes

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

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