High Luminescence Efficiency in MoS2 Grown by Chemical Vapor Deposition
- Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Office of Scientific and Technical Information (OSTI)
- Army Research Lab., Adelphi, MD (United States)
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Univ. of California, Berkeley, CA (United States)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
We report that 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%). Lastly, the discovery of an effective passivation strategy will speed the development of scalable high-performance optoelectronic and electronic devices based on MoS2.
- Research Organization:
- Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
- Grant/Contract Number:
- SC0001088; AC02-05CH11231; SC0004993
- OSTI ID:
- 1557789
- Journal Information:
- ACS Nano, Journal Name: ACS Nano Journal Issue: 7 Vol. 10; ISSN 1936-0851
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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