Anomalous photoluminescence thermal quenching of sandwiched single layer MoS_2
Shakfa, Mohammad Khaled
Ng, Tien Khee
Ooi, Boon S.
KAUST DepartmentComputer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division
Physical Sciences and Engineering (PSE) Division
Permanent link to this recordhttp://hdl.handle.net/10754/625508
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AbstractWe report an unusual thermal quenching of the micro-photoluminescence (µ-PL) intensity for a sandwiched single-layer (SL) MoS2. For this study, MoS2 layers were chemical vapor deposited on molecular beam epitaxial grown In0.15Al0.85N lattice matched templates. Later, to accomplish air-stable sandwiched SL-MoS2, a thin In0.15Al0.85N cap layer was deposited on the MoS2/In0.15Al0.85N heterostructure. We confirm that the sandwiched MoS2 is a single layer from optical and structural analyses using µ-Raman spectroscopy and scanning transmission electron microscopy, respectively. By using high-resolution X-ray photoelectron spectroscopy, no structural phase transition of MoS2 is noticed. The recombination processes of bound and free excitons were analyzed by the power-dependent µ-PL studies at 77 K and room temperature (RT). The temperature-dependent micro photoluminescence (TDPL) measurements were carried out in the temperature range of 77 – 400 K. As temperature increases, a significant red-shift is observed for the free-exciton PL peak, revealing the delocalization of carriers. Further, we observe unconventional negative thermal quenching behavior, the enhancement of the µ-PL intensity with increasing temperatures up to 300K, which is explained by carrier hopping transitions that take place between shallow localized states to the band-edges. Thus, this study renders a fundamental insight into understanding the anomalous thermal quenching of µ-PL intensity of sandwiched SL-MoS2.
CitationTangi M, Shakfa MK, Mishra P, Li M-Y, Chiu M-H, et al. (2017) Anomalous photoluminescence thermal quenching of sandwiched single layer MoS_2. Optical Materials Express 7: 3697. Available: http://dx.doi.org/10.1364/OME.7.003697.
SponsorsKing Abdulaziz City for Science and Technology (KACST); King Abdullah University of Science and Technology (KAUST) (KACST TIC R2-FP-008 and BAS/1/1614-01-01).
PublisherThe Optical Society
JournalOptical Materials Express