Measuring the Edge Recombination Velocity of Monolayer Semiconductors

Peida Zhao, Matin Amani, Der-Hsien Lien, Geun Ho Ahn, Daisuke Kiriya, James P. Mastandrea, Joel W. Ager, Eli Yablonovitch, Daryl C. Chrzan, Ali Javey*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Understanding edge effects and quantifying their impact on the carrier properties of two-dimensional (2D) semiconductors is an essential step toward utilizing this material for high performance electronic and optoelectronic devices. WS2 monolayers patterned into disks of varying diameters are used to experimentally explore the influence of edges on the material's optical properties. Carrier lifetime measurements show a decrease in the effective lifetime, τeffective, as a function of decreasing diameter, suggesting that the edges are active sites for carrier recombination. Accordingly, we introduce a metric called edge recombination velocity (ERV) to characterize the impact of 2D material edges on nonradiative carrier recombination. The unpassivated WS2 monolayer disks yield an ERV ∼ 4 × 104 cm/s. This work quantifies the nonradiative recombination edge effects in monolayer semiconductors, while simultaneously establishing a practical characterization approach that can be used to experimentally explore edge passivation methods for 2D materials.

Original languageEnglish
Pages (from-to)5356-5360
Number of pages5
JournalNano letters
Issue number9
StatePublished - 13 Sep 2017


  • edge effects
  • edge recombination velocity
  • quantum yield
  • Transition metal dichalcogenide
  • WS


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