Effective passivation of exfoliated black phosphorus transistors against ambient degradation

Joshua D. Wood, Spencer A. Wells, Deep Jariwala, Kan Sheng Chen, Eunkyung Cho, Vinod K. Sangwan, Xiaolong Liu, Lincoln J. Lauhon, Tobin J. Marks, Mark C. Hersam

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774 Citations (Scopus)

Abstract

Unencapsulated, exfoliated black phosphorus (BP) flakes are found to chemically degrade upon exposure to ambient conditions. Atomic force microscopy, electrostatic force microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy are employed to characterize the structure and chemistry of the degradation process, suggesting that O2 saturated H2O irreversibly reacts with BP to form oxidized phosphorus species. This interpretation is further supported by the observation that BP degradation occurs more rapidly on hydrophobic octadecyltrichlorosilane self-assembled monolayers and on H-Si(111) versus hydrophilic SiO2. For unencapsulated BP field-effect transistors, the ambient degradation causes large increases in threshold voltage after 6 h in ambient, followed by a ∼103 decrease in FET current on/off ratio and mobility after 48 h. Atomic layer deposited AlOx overlayers effectively suppress ambient degradation, allowing encapsulated BP FETs to maintain high on/off ratios of ∼103 and mobilities of ∼100 cm2 V-1 s-1 for over 2 weeks in ambient conditions. This work shows that the ambient degradation of BP can be managed effectively when the flakes are sufficiently passivated. In turn, our strategy for enhancing BP environmental stability will accelerate efforts to implement BP in electronic and optoelectronic applications.

Original languageEnglish
Pages (from-to)6964-6970
Number of pages7
JournalNano letters
Volume14
Issue number12
DOIs
Publication statusPublished - Dec 10 2014

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Keywords

  • Phosphorene
  • atomic layer deposition
  • field-effect transistor
  • stability
  • water

ASJC Scopus subject areas

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

Cite this

Wood, J. D., Wells, S. A., Jariwala, D., Chen, K. S., Cho, E., Sangwan, V. K., Liu, X., Lauhon, L. J., Marks, T. J., & Hersam, M. C. (2014). Effective passivation of exfoliated black phosphorus transistors against ambient degradation. Nano letters, 14(12), 6964-6970. https://doi.org/10.1021/nl5032293