Defects activated photoluminescence in two-dimensional semiconductors: interplay between bound, charged, and free excitons
By S. Tongay, Joonki Suh, C. Ataca, W. Fan, A. Luce, Jeong Seuk Kang, Jonathan Liu, C. Ko, Rajamani Raghunathanan, Jian Zhou and 4 more. Scientific Reports, 2013
1,026 citations recorded by the source corpus.
Point defects in semiconductors can trap free charge carriers and localize excitons. The interaction between these defects and charge carriers becomes stronger at reduced dimensionalities and is expected to greatly influence physical properties of the hosting material. We investigated effects of anion vacancies in monolayer transition metal dichalcogenides as two-dimensional (2D) semiconductors where the vacancies density is controlled by α-particle irradiation or thermal-annealing. We found a new, sub-bandgap emission peak as well as increase in overall photoluminescence intensity as a result of the vacancy generation. Interestingly, these effects are absent when measured in vacuum. We conclude that in opposite to conventional wisdom, optical quality at room temperature cannot be used as criteria to assess crystal quality of the 2D semiconductors. Our results not only shed light on defect and exciton physics of 2D semiconductors, but also offer a new route toward tailoring optical properties of 2D semiconductors by defect engineering.
Subfields: Materials Chemistry, Renewable Energy, Sustainability and the Environment
View Paper: https://www.semanticscholar.org/paper/df96452fb8147e6a8ab1f4547af2c6c61b471553
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In Renewable Energy, Sustainability and the Environment
Citations in the corpus
- Defect engineering of two-dimensional transition metal dichalcogenides (2016, methodology): “a PL peak is observed with an energy below the band gap value (see figure 9(a)), attributable to neutral excitons bound to defects [13, 125].”
- Emerging nanofabrication and quantum confinement techniques for 2D materials beyond graphene (2018, background): “5d) in addition to sharpening of the spectral line suggesting quantum emission of single photons.158 A similar strain-induced phenomena has been observed in strained WSe2, 159 suggesting it is applicable for many TMDCs.”
- From two-dimensional materials to their heterostructures: An electrochemist's perspective (2017, background): “The shape and intensity of the PL spectra varies substanially due to the 2D material–substrate interactions [69,146,150], emperature [148], defect density [56,166], and surrounding media 167].”
- Valley-polarized exciton–polaritons in a monolayer semiconductor (2017, background): “A low-temperature defect state [42] (labeled as D) is present in the bare MoS2 which does not exhibit polarization, confirming the polarization arises from the valley-pumped exciton-polaritons and not measurement bias.”
- Strong photoluminescence enhancement of MoS(2) through defect engineering and oxygen bonding. (2014, neutral): “inbothpristine/as-grownMoS2 20 22 andelectron beam/plasma-irradiated samples.(23,24)”