High Luminescence Efficiency in MoS2 Grown by Chemical Vapor Deposition

Matin Amani, Robert A. Burke, Xiang Ji, Peida Zhao, Der Hsien Lien, Peyman Taheri, Geun Ho Ahn, Daisuke Kirya, Joel W. Ager, Eli Yablonovitch, Jing Kong, Madan Dubey, Ali Javey*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

124 Scopus citations


One of the major challenges facing the rapidly growing field of two-dimensional (2D) transition metal dichalcogenides (TMDCs) is the development of growth techniques to enable large-area synthesis of high-quality materials. Chemical vapor deposition (CVD) is one of the leading techniques for the synthesis of TMDCs; however, the quality of the material produced is limited by defects formed during the growth process. A very useful nondestructive technique that can be utilized to probe defects in semiconductors is the room-temperature photoluminescence (PL) quantum yield (QY). It was recently demonstrated that a PL QY near 100% can be obtained in MoS2 and WS2 monolayers prepared by micromechanical exfoliation by treating samples with an organic superacid: bis(trifluoromethane)sulfonimide (TFSI). Here we have performed a thorough exploration of this chemical treatment on CVD-grown MoS2 samples. We find that the as-grown monolayers must be transferred to a secondary substrate, which releases strain, to obtain high QY by TFSI treatment. Furthermore, we find that the sulfur precursor temperature during synthesis of the MoS2 plays a critical role in the effectiveness of the treatment. By satisfying the aforementioned conditions we show that the PL QY of CVD-grown monolayers can be improved from ∼0.1% in the as-grown case to ∼30% after treatment, with enhancement factors ranging from 100 to 1500× depending on the initial monolayer quality. We also found that after TFSI treatment the PL emission from MoS2 films was visible by eye despite the low absorption (5-10%). The discovery of an effective passivation strategy will speed the development of scalable high-performance optoelectronic and electronic devices based on MoS2.

Original languageEnglish
Pages (from-to)6535-6541
Number of pages7
JournalACS Nano
Issue number7
StatePublished - 26 Jul 2016


  • biexcitonic recombination
  • chemical vapor deposition
  • MoS
  • quantum yield
  • radiative lifetime
  • transition metal dichalcogenide


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