Abstract
Achieving localized light emission from monolayer two-dimensional (2D) transition metal dichalcogenides (TMDs) embedded in the matrix of another TMD has been theoretically proposed but not experimentally proven. In this study, we used cathodoluminescence performed in a scanning transmission electron microscope to unambiguously resolve localized light emission from 2D monolayer MoSe2 nanodots of varying sizes embedded in a monolayer WSe2 matrix. We observed that the light emission strongly depends on the nanodot size, wherein the emission is dominated by MoSe2 excitons in dots larger than 85 nm and by MoSe2/WSe2 interface excitons below 50 nm. Interestingly, at extremely small dot sizes (<10 nm), the electron energy levels in the nanodot become quantized, as demonstrated by a striking blue-shift in interface exciton emission, thus inducing quantum confined luminescence. These results establish controllable light emission from spatially confined 2D nanodots, which holds potential to be generalized to other 2D systems toward future nanophotonic applications.
| Original language | English |
|---|---|
| Journal | ACS Photonics |
| DOIs | |
| State | Accepted/In press - 2024 |
| Externally published | Yes |
Funding
The authors would like to acknowledge the financial support from National Science Foundation (NSF) through CAREER DMR-1654107, CAREER DMR-2340733, DMR-2429280 and Penn State 2D Crystal Consortium \u2013 Materials Innovation Platform (2DCC \u2013 MIP) under DMR-1539916 and DMR-2039351. We gratefully acknowledge the Materials Characterization Lab (MCL) platforms of Penn State University for the characterization equipment. N. A. also acknowledges the Fulbright Scholar program grant she received through the Franco-American Fulbright Commission. D. R. H. also acknowledges start-up funds from the Penn State Eberly College of Science, Department of Chemistry, and Materials Research Institute. N. Trainor acknowledges the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE1255832H. This work has received support from the National Agency for Research under the program of future investment TEMPOS-CHROMATEM (reference no. ANR-10- EQPX-50), the JCJC grant SpinE (reference no. ANR-20-CE42-0020), and from the European Union\u2019s Horizon 2020 Research and Innovation Program under grant agreements 823717 (ESTEEM3) and 101017720 (EBEAM). D. J. and G. K. acknowledge primary support for this work by the Asian Office of Aerospace Research and Development (AOARD) of the Air Force Office of Scientific Research (AFOSR) FA2386-20-1-4074 and partial support from FA2386-21-1-406. K. W. and T. T. acknowledge support from the JSPS KAKENHI (Grant Numbers 20H00354, 21H05233 and 23H02052) and World Premier International Research Center Initiative (WPI), MEXT, Japan. F. H. and Y. W. acknowledge computational resources from the Texas Advanced Computing Center. Part of the modeling work was supported by computational resources from a user project at the Center for Nanophase Materials Sciences (CNMS), a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory, and also partially by user project R0076 at the 2DCC-MIP. The authors would like to acknowledge the financial support from the National Science Foundation (NSF) through CAREER DMR-1654107, CAREER DMR-2340733, DMR-2429280 and Penn State 2D Crystal Consortium\u2500Materials Innovation Platform (2DCC\u2500MIP) under DMR-1539916 and DMR-2039351. N. Alem also acknowledges the Fulbright Scholar program grant she received through the Franco-American Fulbright Commission. D. Reifsnyder Hickey also acknowledges start-up funds from the Penn State Eberly College of Science, Department of Chemistry, and Materials Research Institute. N. Trainor acknowledges the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE1255832H. This work has received support from the National Agency for Research under the program of future investment TEMPOS-CHROMATEM (reference no. ANR-10- EQPX-50), the JCJC grant SpinE (reference no. ANR-20-CE42-0020), and from the European Union\u2019s Horizon 2020 Research and Innovation Program under grant agreements 823717 (ESTEEM3) and 101017720 (EBEAM). D. Jariwala and G. Kim acknowledge primary support for this work by the Asian Office of Aerospace Research and Development (AOARD) of the Air Force Office of Scientific Research (AFOSR) FA2386-20-1-4074 and partial support from FA2386-21-1-406. K. Watanabe and T. Taniguchi acknowledge support from the JSPS KAKENHI (Grant Numbers 20H00354, 21H05233, and 23H02052) and the World Premier International Research Center Initiative (WPI), MEXT, Japan. F. Habis and Y. Wang acknowledge computational resources from the Texas Advanced Computing Center. Part of the modeling work was supported by computational resources from a user project at the Center for Nanophase Materials Sciences (CNMS), a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory, and also partially by a user project R0076 at the 2DCC-MIP.
Keywords
- cathodoluminescence
- in-plane heterostructures
- interface excitons
- nanodots
- quantum confinement
- scanning transmission electron microscopy