Measuring the Edge Recombination Velocity of Monolayer Semiconductors.

Nano Lett

Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.

Published: September 2017

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. WS 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, τ, 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 WS monolayer disks yield an ERV ∼ 4 × 10 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.

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http://dx.doi.org/10.1021/acs.nanolett.7b01770DOI Listing

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