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
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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