Investigation of Band-Offsets at Monolayer-Multilayer MoS2 Junctions by Scanning Photocurrent Microscopy

Sarah L. Howell, Deep Jariwala, Chung Chiang Wu, Kan Sheng Chen, Vinod K. Sangwan, Junmo Kang, Tobin J. Marks, Mark C. Hersam, Lincoln J. Lauhon

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87 Citations (Scopus)

Abstract

The thickness-dependent band structure of MoS2 implies that discontinuities in energy bands exist at the interface of monolayer (1L) and multilayer (ML) thin films. The characteristics of such heterojunctions are analyzed here using current versus voltage measurements, scanning photocurrent microscopy, and finite element simulations of charge carrier transport. Rectifying I-V curves are consistently observed between contacts on opposite sides of 1L/ML junctions, and a strong bias-dependent photocurrent is observed at the junction. Finite element device simulations with varying carrier concentrations and electron affinities show that a type II band alignment at single layer/multilayer junctions reproduces both the rectifying electrical characteristics and the photocurrent response under bias. However, the zero-bias junction photocurrent and its energy dependence are not explained by conventional photovoltaic and photothermoelectric mechanisms, indicating the contributions of hot carriers. (Graph Presented).

Original languageEnglish
Pages (from-to)2278-2284
Number of pages7
JournalNano letters
Volume15
Issue number4
DOIs
Publication statusPublished - Apr 8 2015

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Keywords

  • MoS
  • SPCM
  • TMDC
  • dichalcogenides
  • energy conversion
  • field-effect transistor
  • gate-tunable
  • heterojunction
  • photothermal
  • photovoltaic
  • scanning photocurrent microscopy
  • two-dimensional

ASJC Scopus subject areas

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

Cite this

Howell, S. L., Jariwala, D., Wu, C. C., Chen, K. S., Sangwan, V. K., Kang, J., Marks, T. J., Hersam, M. C., & Lauhon, L. J. (2015). Investigation of Band-Offsets at Monolayer-Multilayer MoS2 Junctions by Scanning Photocurrent Microscopy. Nano letters, 15(4), 2278-2284. https://doi.org/10.1021/nl504311p