Auger Recombination in Chemical Vapor Deposition-Grown Monolayer WS2

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• 作者：Paul D. CunninghamKathleen M. McCreary ; Berend T. Jonker
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：December 15, 2016
• 年：2016
• 卷：7
• 期：24
• 页码：5242-5246
• 全文大小：369K
• ISSN：1948-7185

文摘

Reduced dimensionality and strong Coulombic interactions in monolayer semiconductors lead to enhanced many-body interactions. Here, we report Auger recombination, i.e., exciton–exciton annihilation, in large-area chemical vapor deposition-grown monolayer WS₂. Using ultrafast spectroscopy, we experimentally determine the Auger rate to be 0.089 ± 0.001 cm²/s at room temperature, which is an order of magnitude greater than the bulk value. This nonradiative recombination pathway dominates, regardless of excitation energy, for exciton densities greater than 8.0 ± 0.6 × 10¹⁰ cm^–2 and below the Mott density. Higher-energy excitation above the A exciton resonance may initially produce a hot electron–hole gas that precedes exciton formation. Therefore, we use resonant excitation of the A exciton to ensure accuracy and avoid artifacts associated with other photogenerated species.